The ideal endpoint of evolution will have regrowing limbs and organs, acid abs poison breath, laser eyes, hard, chitinous exoskeletons, little monkey servants who bring you cheese look what about this isn't crab

Sure, but that doesn't actually happen in reality, that things just stop changing. Occasionally, you get rather isolated ecosystems where the changes go back and forth in a mostly self-contained manner and then adaptation might plateau for a bit, but at some point, a lightning or an earthquake or something will strike and then it's back to adaptation.
Well, and those species which were the most adapted to this isolated ecosystem are also likely to die out then, rendering this temporary endpoint not exactly "ideal" either.

But it's also not one singular endpoint either. Diversity is itself a strength, which helps species survive. This is particularly important where there is change, because external influences will affect different members of this species more or less strongly.
But even without change, splitting the work is beneficial. This can be as mundane as not everyone carrying around the equipment for bringing out the babies. But in particular with societal structures, it can also mean that the big muscle folks might do the muscly tasks and the big brain folks do the brainy tasks and those with claws for hands open up all the tin cans.
Evolution will not push past that to arrive at some hypothetical "ideal endpoint", because that society with work splitting is fitter for survival than a monoculture would be.