I always ran positive and negative energy as morally neutral. They may be used in different ways, some good, some evil, just like any other tool. Undead, and creation of them, is evil not because it uses negative energy, but because it uses it to create a mockery of life, an abomination, a thing that is dead but behaves as alive. Positive energy may be used against its nature, too, but it is not something as grounded in fantasy as undead creation - I don't remember ever encountering it in my games.
In this model, it is also obvious that there is no such thing as "positive energy undead", "deathless" etc. - creatures animated by positive energy are just living things. Positive energy giving life is a part of life cycle, as is negative energy taking it. What is morally wrong is subverting this flow.
In this model, it is also obvious that there is no such thing as "positive energy undead", "deathless" etc. - creatures animated by positive energy are just living things. Positive energy giving life is a part of life cycle, as is negative energy taking it. What is morally wrong is subverting this flow.