[howaboutnope]

I hate software bloat and thrown away milliseconds, but even then I realize that our visual cortex is really good at noticing movement, but hasn't had any experience in the last millions of years with stuff just popping up out of nowhere or teleporting. I know nothing about usability but just from knowing that, and my own experience, I can't dismiss any and all "useless" animations out of hand. There was a time when we couldn't afford them, now it depends.

Maybe this would be a useful way to look at it: if the average disorientation caused by instant change (which also depends on whether the change is predictable, makes other things change position, etc.) takes longer to recover from than the shortest animation/fade you could come up with, have a transition.

(but even then it doesn't hurt to gate all of that behind a global configuration option, IMO, and if you want to be really fancy make it a float, not a boolean)