Why is creating undead Evil?

[NigelWalmsley]

I would and have ruled that Animate Dead type spells fail on remains where the soul is in a living body, such as True Resurrection, Clone, etc. As such, ambiguity is removed; the spell unambiguously soul traps the original owner.

Sure, but again, that's not RAW. You certainly could rule things in a way that there is a single objective soul that is in one place at a time and has consistent interactions for all the various spells. But the rules clearly don't (or don't clearly) work that way now.