Remus Lupin
Adventurer
Between the OGL and farming out Dungeon & Dragon magazine to Paizo, they basically handed the keys to the D&D business to them.
But the Paizo took the keys and drove a very successful new version of the rules onto the lot, one that for many of us is superior to the new model that WotC tried to sell us.
Whatever the other merits or demerits of the OGL might be, for me the fact that we as players of D&D weren't put in a position of either having to accept the new model or continue to drive our unsupported old jalopy around is the greatest advantage FOR THE PLAYER of the OGL. It's not much of an advantage for WotC, I grant, but that's because, I think, WotC forgot why it created the OGL in the first place and didn't use it properly.
But from the perspective of the player, the OGL was pure win.