An Attack on "Alignment"

[Yitzi]

Having magic weapons that deal extra damage against evil outsiders are just fine. You can have these weapons in your campaign or not. But making outsiders so that you need weapons with Good enchantments to harm them makes it difficult to remove such weapons from the game if you don't want them.

Such outsiders also only make sense if they're protected by the power of evil in some way. In an alignmentless setting, those outsiders would either be absent, or lack said DR.