100% is defined by items you have to obtain, and Ganon gives you nothing. I'd be very-much against this change.
Also, OoT3D has been doing Ganonless in 100% for a long time now...
All Dungeons is part of the 100% definition, even though the dungeons aren't items. Yes, they
give you items, but completing the dungeons is a separate requirement. If you got all stones and medallions through other means (for example if RBA wasn't banned), you'd still have to beat them anyway. 100% isn't really just about items, although you're right, is is primarily about items.
EDIT: Oh whoops! I guess All Dungeons isn't currently part of the definition. Either I'm crazy, or the definition was rewritten somewhere down the line or something. But anyway, I think All Dungeons should be a requirement simply because they are major progression points in the story. Same could be said about fighting Ganon. Call it arbitrary if you'd like, but 100% is an entirely subjective category anyway, since percentages are not defined by the game.