>>39256229For the same reason there's a whole list of mechanics in GTA IV that aren't in GTA V. For the same reason Smash Bros. Ultimate had to cut back on the amount of new stages, the amount of new modes, and why its new modes so heavily reuse core assets instead of having new ones, all while heavily reusing Smash 4s assets.
There comes a point where making considerations for all previous aspects of design inflates a project too much for even the highest of budgets or development time to compensate. No amount of "just throw money at it lol" (which doesn't work as well as you'd think anyway) will change what having too large a scope does to a project.
There are almost 1,000 unique Pokemon models CURRENTLY. Each one of those has a hand crafted animation that is species specific, for the following actions: idle, idle fidget, physical attack, special attack, sleeping, walking, running, positive Refresh response, negative refresh response. Let's say you want to add ONE new animation to that list, you now have just added a 1,000 animation workload to your development.
There comes a point where this kind of thing is unfeasible, no matter how big your project is. Same for Smash Bros. which only got every fighter because it pulled back the brakes everywhere else. Same for GTA which only got V to the scale it was because it pulled back on the macro mechanics IV had.