In past games such as Oblivion
Lol, in the past we never had full access to the Daedra of Forbidden Knowledge and Secrets.

Seriously though, let the past stay in the past. Many good rpg's have this feature, and most of them don't do it nearly as well as Beth did it. It is very easy to rp a daedra wiping away certain knowledge for your benefit. And it breaks NOTHING. Its not like I can turn a warrior into a mage with this, since we're still limited by magicka stamina and health. Vice versa is also true. You gotta look at it from all angles my friend. The only people that can really make super drastic changes are level 81 or so characters. And that is a pretty small amount of people. The ones who got there "legitly" anyway. The ones who got there through Oghma infinium probably dont give a rats ass about doing things the normal rpg friendly way anyway.