Fixing the Divide... complete item overhaul.
What if... All items did ADAPTIVE damage... making every item viable for every champion. There is always a big debate that Riot is biased towards AD champions and items and yes, they are but what if, all items in the game did adaptive damage. That would allow for a high degree of experimentation in the community and may ignite the old trend of fun, off-meta builds. Nerfing and buffing items as they come up, would be a lot easier as well, as Riot could more clearly see issues.
No AD No AP Just Adaptive Damage and then maybe FINALLY Riot could see where all the problem champions are and fix their kits, rather then messing about with the items themselves.