I've allowed psionics in my campaigns, but then again, I've mostly had them used by NPCs. My players haven't had much of an inclination to use them. I've also allowed all the magics and ninjas and such. But then again, I really don't agree with what I have heard others call the "classic fantasy campaign."
On the flip side, when you consider that my first D&D book was Oriental Adventures followed by the DMG so I had no desire to recreate a King Arthur or similar setting. I wanted something that was more personalized for those in my group and none of us wanted to search for the Holy Grail. We wanted something a lot different.
I think, though, that that's the beauty of how far this game has come. Different campaigns can use the rules they lke without having to use the rules that don't fit in.
On the flip side, when you consider that my first D&D book was Oriental Adventures followed by the DMG so I had no desire to recreate a King Arthur or similar setting. I wanted something that was more personalized for those in my group and none of us wanted to search for the Holy Grail. We wanted something a lot different.
I think, though, that that's the beauty of how far this game has come. Different campaigns can use the rules they lke without having to use the rules that don't fit in.