Out of my last 25 games I've played...
I've made it to the 30 minute mark 9 times, the 35 minute mark 2 times, and the 40 minute mark 0 times. When I played scaling champs, win or lose, I don't have fun cause I never get my items. And if I do, it's when the enemy is breaking down my Nexus or we're breaking theirs.
If Riot wants faster games then reduce costs of items and increase exp gain across the board, but decrease gold gained from snowballing. That way we don't have to sit in games for an hour, but the shorter games we're a part of aren't stomps.