The devs decide to add more pixels. The reasons for this, the decisions why to add pixels at all, where to add them, which models to add them to, how many to add to balance perceived demand vs. internal demand vs. resource cost, are not fully understood by us, or even by the participants in the decision process. Individual decisions are made independently, though within an overall system in which senior team members and ultimately senior management must approve them, or at least not countermand them.
In most cases, the general policy of adding more pixels results in ... adding more pixels. Just that. Models are made smoother, more polygons, more fluid movements. We players pay for this in heavier resource costs. We lose FPS. I have known several in-game friends who can no longer play because their PCs could no longer keep up with the game. That is a cost. But the models themselves are recognisable as the same entities, just with a higher resolution.
Sometimes this goes wrong. Sometimes, as with the examples Quintessence points out above, they try to improve the quality of the model, but introduce new problems in the process. This is inevitable in development. We can and should ask for a fix, and if it happens too often, questions might be asked about competence, but mistakes happen, nobody intended it, and it is mean to try to focus blame on the people in such cases.
Sometimes, however, this process is abused. Instead of a good-faith effort to upscale the resolution of a model, some graphics worker will try to remove the model and substitute his/her own. This is a deliberate act. When this changeling is accepted and replaces something to which people have formed and attachment in game, it is appropriate to call it out as a deliberate act.
How can we know which is which? I'm not sure there is a full operational definition, but these questions are the start: 1. Is this new model clearly the same entity as the original? 2. Was it possible for a competent practitioner attempting to perform a good-faith improvement to retain the character of the original model?
Smoochums was an interesting recent case, more interesting because it was a new pet. Why would Blizzard have wanted to spend money and time changing a model just a few months old? This was not a 2004 prairie dog that looked inpired by a Euclid theorem. There were no problems with the model. Nobody was complaining about it.
When a project manager is assigned new people, the first problem is making them useful. Even when they have superior skills, they will be unfamiliar with the processes, tools, standards, and integration contstraints of the environment. Blizzard famously cited this as a reason for issues during Warlords. I understand this. It's well known in the business that adding more people to a late project makes it later. And, of course, by definition, most people don't have superior skills. So a team lead or PM will assign newbies to small, confined projects that will have minimal impact on others. Often, these projects are effectively make-work, that serves mainly as training rather than output. Perhaps Smoochums was such a case, though even that is odd; surely there were other more deserving targets?
As a former team lead/PM/director myself for decades, I am very familiar with the syndrome. Often, new people want to make their mark by showing off that they can do better than their predecessors. And often, they fail.
In any case, what happened here was not a good-faith upgrade of the model. Smoochums was removed, and replaced with something entirely different.
Smoochums happened to get the Twitter-mob treatment, and Blizzard backed down fast, with Lore finally posting a #Justicefor Smoochums tag.
Here's a case that didn't get the Twitter-mob treatment:
https://eu.battle.net/forums/en/wow/topic/17620702030
First day I played this game back in April 2008 I was made so happy by the cat lady just outside of Northshire Abby cus I was able to buy a silver tabby. Thing is I turned to Warcraft to try and cheer myself up cus my real life silver tabby had just died. Suffice to say the 38 silver was well invested cus that cat pretty much has been by my side the whole game.
Sadly I had to give up my female human characters cus they changed the appearance and I am now unable to play the old character model. Anyway... I logged in after the patch and shock horror they have now gone an fluffed up the silver tabby to the point I no longer relate to him. Worse, he now doesn't run he glides and I noticed tonight he doesn't even leave footprints in the snow anymore.
I keep looking at him and am bewildered why the change. Its like he's a fluffy toy now and not the lovable silver tabby I had by my side for the last ten years.
There is all the difference in the world between a good-faith model update that did not go well, and a bad-faith misrepresentation of a replacement as an update.
Nobody could mistake the new Emperor Crab model for the old one. The current model looks nothing like the old one. The current model is not an upgrade. The Emperor Crab model was destroyed, and this replaces it. Was there anything wrong with the original model? No. Was anyone complaining about it? No. On the contrary, I, at least, liked it; it was one of my favourites. (Yes, tastes are tastes.)
When addressing changes, and the motivations for them, it is entirely appropriate to distinguish between honest mistakes and dishonest arrogance imposing changes on people who have formed attachments. I would like to see Lore tweeting out a #JusticeFor tag for all the models that have been deliberately removed. #JusticeforSilverTabby #JusticeforEmperorCrab