To answer your question...
I have learned through many many years of experience and research that keeping snakes in terrariums with any substrate other than newspaper is actually not very healthy for the snakes for a multitude of reasons. Cages made specifically for snakes, like the Neodesha cages, for instance, are optimal, however, some snakes do not fare well in glass front cages and actually prefer the bins.
Most glass terrariums require screen-top lids for ventilation and to allow for overhead lighting/heat. This makes it difficult to regulate floor heat and humidity within the cage... especially since heat rises, right out of the cage. Lighting also, can cause major stress issues for snakes since they would need to sit in the hot spot to bask, but snakes like boa constrictors and ball pythons (and several other species) are nocturnal and do not enjoy sitting in direct sunlight. Using an actual light in the cage is a bad idea. You can use the UV heat emitters, but like I said before, regulating floor temperature can still be an issue.
The truth is, snakes don't absorb their heat from sitting in the sun. They absorb their heat by soaking it up from the already heated ground/rocks. Hot rocks (commonly used to heat and decorate a cage) are a death sentence for ANY reptile and should NEVER be used. The sheer number of snakes and lizards that have died because of those darned electronic rocks is unfathomable. They heat spike and are very difficult to regulate. I've actually seen snakes (not my own) with burns so bad on it's stomach that the snake had to be put to sleep. The solution, of course, are under tank heat pads. These are great! best source of heat for a snake, EVER! But, the problem is that if you dump a bunch of substrate in your cage with the UTH underneath, the snake either has to dig its way to get to the heat, or it gets a very poor source of heat unless you crank the darned thing up.
Substrate, of course, is a beast of another kind. First of all, many types of substrate are dangerous, and often times deadly for snakes. You can use peat moss, jungle bed, aspen, or cypress mulch, but they come with a whole host of problems. No matter what you do with it, mulch will bring in and hide mites and other insects... and the insects it doesn't bring in, will often times find their way into the snake cages to lay a few eggs for good measure. My peat moss (which I use for my Ameivas) seems to come with a nice collection of carpet beetle eggs... which hatch into larvae that I have to set traps for... and they are relatively nasty little buggers. You absolutely can't use anything like that ground Wallnut hull or calcite. That stuff gets stuck in the snake's vent and can kill them.... pine and cedar bedding kills snakes too. Snakes can also ingest their bedding and get plugged up and die if they do so. I feed in my cages for the sake of the snakes stress and comfort levels, and the last thing I want is for them to eat some bedding and die.
Another common problem with substrate that most people don't think about is that every single time the snake pees or poops you HAVE to clean and change the entire cage. The amount of dust, mold, mildew, and bacteria that builds up if you don't is phenomenal. That also means pulling out each and every one of your "decorations", etc. Dumping the cage, scrubbing the cage, and refilling it with new substrate. If you think that spot cleaning is enough, you've apparently never seen how much liquid comes out of a snake when it pees or poops.... especially not a 45 lb snake.... or a 100 lb snake, for that matter. Of course, if you opt to simply spot clean every time the snake does it's business, it's only a matter of time before your snake is at risk for a variety of bacterial infections, skin infections, and respiratory conditions caused by mold, mildew, etc.
So why do I use newspaper? Well, because I care about the health of my animals. Every time my snake goes to the bathroom, I can quickly and easily clean the cage, thoroughly. No trying to scrape pee-soaked substrate dust out of corners. If any of the snakes gets mites, I will know instantly because I can easily see them and they can't hide or lay eggs in the substrate, which also makes it easier to get rid of them. And quite frankly, having tried a variety of substrates with a variety of snakes, I can honestly say that the snakes just don't care. Body language says a lot with snakes. If it bothered them, I would know because I spend a lot of time with them. I know how they act when they are bothered. And if switching from substrate to newspaper bothered them, I would have known.
A lot of people make the argument "Well, now they can't dig!" I own boa constrictors. BCI's don't burrow. If they want, there is plenty of paper, however, for them to go under it if they like. Occasionally some do, but most of mine prefer not to. The newspaper also allows for more creativity, in my opinion. Unlike substrate, newspaper will hold it's shape if it's worked with. I have an "artist" snake that likes to make "caves" out of his newspaper... and then he shoves his waterbowl in front of the "cave" so he can wait all stealthily for a snack to come to the "watering hole". I also have a snake that has figured out that if he separates the paper so that there is a gap in the middle, he can pee on one piece and it will absorb all the pee and he can go sit on the dry piece. To be honest, I am not sure many of my snakes would like it if I put substrate in their cages. I have quite a few that are neat freaks now. I can tell if anyone goes to the bathroom because the instant I go into the room and they see me, they let me know so I can clean them.
Now... back to the bins. There is nothing out there that holds humidity and heat quite as well as the bins. Before switching my snakes out of terrariums, my snakes would regularly have bad sheds. Even with misting and soaking, occasionally the sheds would just be bad. Ever since I switched, I haven't had a bad shed once. In fact, I get perfect, single piece 9-10 foot long sheds off of a couple of my snakes now.
Ten foot long shed.. draped over my 5' tall iguana cage.
When I got my first snake, I kept him in a terrarium with substrate and decor. However, because of keeping him in a setup that pet stores promote (for the sake of making money, mind you), he suffered a number of health problems until I switched him to a bin with newspaper. Since converting him to the type of setup he has now, he hasn't had a single health issue.
As far as decor? The snakes don't really seem to care. I take them out enough to stimulate them, and quite frankly, when they did have stuff in their cage, they didn't really do anything with it either. They do, however, seem to enjoy going to play at the park and climbing on the jungle gym there. I've often thought about turning my extra bedroom into a play-room for the snakes with stuff to play on. Sometimes I give them large cardboard boxes to play in and they really seem to get a kick out of that. But it seems like when they have stuff in with them, they get bored with it. I think it's the excitement of something new that stimulates them more than just having a couple of fake plants in their cage. Besides, my snakes are captive bred, as were their parents. They've never been wild and are accustomed to the comforts of the modern home... which includes laying in my bed, snuggling up with my blankets, and watching TV.... and of course, my snakes don't have to kill their own food, so half of them don't even bother constricting anymore. They just gently take it from my hand. Considering that a couple of my snakes hate being in grass, I think that says a lot about how they really feel about the idea of me "naturizing" their homes.
So, think what you will about people who keep their snakes in bins with newspaper. I don't do it for me. Trust me, I would love more than anything to keep my snakes in beautiful zoo style enclosures. In fact, I LONG to have beautiful zoo style enclosures. But I choose to keep my snakes the way I do for the safety and health of my snakes. Between my husband and I, we have been keeping reptiles for 21 years. Even professional herpetologists I know come over and praise our setup. All in all, my snakes are my babies. I do not consider them mindless. I do not consider them livestock. They are individuals with personalities, likes, and dislikes. If I did not care about them, I would not care enough about their health to put my own desires for the appearance of their homes aside.
BTW, that rack of tubs in the back of those photos with the closed in sides isn't used to house snakes permanently. Someone gave that to us but we don't like how the snakes get no light with it so I just use it to hold my Afrock when I'm cleaning his cage so that he doesn't tear up the room while I'm not looking.
Proud Suggie Mommy of Lilo & Stitch 
) - His name is Begoli (he picked it himself.... long story but he just refuses to come to his *real* name Ollie lolol)
