Why is creating undead Evil?

[Bohandas]

Heck, Xeg-Yi Energon is made of Negative Energy, but its alignment is "Always neutral", and neither summoning nor calling it to Material Plane count as [Evil] act

Not only made of negative energy but also specifically driven to negate positive beings (particularly its positive counterpart) as in the second theory

that it drives these entities to conduct evil acts (...creation of other evil entities, etc)

It should also be pointed out that this part of the second theory relies on circular reasoning.

EDIT:
Also, the first theory, the one about an evil spirit powering the undead, is a non-starter because then the undead would be vulnerable to Banishment and Protection from Evil