I seem to recall there being "rules" for magic item creation in the 2e DMG, but they were very mythological in feel. Things like having to get the footfall of a cat, with it being up to the player to decide how getting such a thing was possible. Definitely nothing like magic item creation in 3e. A large part of me wants to go back to that sort of magic item creation--but that still assumes magic items are very rare, rather than a given.
Oh, that I like!
Yeah, this was the main reason for permanency. I'm well aware that people will be buffing themselves with it--but with your idea of using an attunement slot, that keeps permanent spells to a reasonable maximum.
Well, in the particular case of detect magic, there are a fair number of classes who basically can get that permanently already--warlocks can use it at will as early as 2nd level, for instance, via Eldritch Sight. So it's mostly a case of what sort of spells would be too OP if gotten permanently, especially when considering magic items that do the same thing.
That's another strong possibility. Thoughts, everyone?