I have to admit that I do have an axe to grind. I've always disliked the outsider type, even more than I've disliked all the other redundant or arbitrary types. The outsider type not only includes fiends, celestials, inevitables, proteans, aeons, genies, jyoti, shae, and so on, but also random creatures that could just as easily be animals like fire snakes and tenebrous worms. I'd prefer to just deprecate the outsider type completely. Fiends and Celestials can become their own type, Inevitables and other lawful outsiders can become constructs, proteans and other chaotic outsiders can become aberrations, Aeons and Genies and Shae and whatever can become Fey, while all the rest can become magical beasts and monstrous humanoids and whatnot. You don't even need to change their statistics if we separate creature type from class features: e.g. the Shae becomes "N Medium fey (augmented outsider, extraplanar)," where "augmented X" indicates it uses the features of X type instead of its current type.