Make ADC the fastest class in the game and compensate by....
removing/nerfing crit. nerfing ranged dmg to towers. buff melee dmg to towers.
The result of this is that adc's stop bitching about peel, melees have a set in stone role to play and have something to offset their kitability. Adc's have to be more aggressive at the same time as well because they cant let the melees die as they are now the ones who destroy structures and must at the same time target the enemy melees. Melee's job is to be tough, survive and build some attack speed. Tank's job? Engage. Set fights up.
Side effect: ad assassins become overpowered and must be nerfed (thank the lawd. fuck you talon, riven and zed) ap burst mages take over the role of assassination.