As some people may know, Riot created League and took some inspiration from Valve's game Dota. After all, Dota is the big brother to all MOBA's.
At this point Riot has lost their way in my opinion. I say the solution is to look at Dota again because when I occasionally play Dota, the games last as long as they are projected to, and a lot of the time longer. Games of Dota (that I play) are 40 minutes to an hour. People still snowball hard too. But the reason why games end slowly is because items cost a butt-ton of gold. There is also another tier of items, with those final-tier ones having enough importance to make them a necessity (sometimes).
Also on another point, crit chance between items and passive abilities doesn't stack, but the damage multiplier is higher, so there is a bigger risk-reward aspect in it.
DISCLAIMER FOR RIOT: THIS DOES NOT MEAN REMOVE MMR MATCHMAKING IN NORMS!