I'm in favor of keeping the game at BELOW 25 minutes.
Reason 1 - Attention Span The average human attention span is literally 10-20 minutes, and within an hour of a class you will only remember.. 20 minutes of it lol This goes to say, league requires an intense amount of concentration whether you're playing casually or competitively.
Reason 2 - More games mean more accurate matchmaking Honestly people complain about two things, matchmaking balance, and queue times. Currently the game is favoring queue times over matchmaking balance. There is never a good balance between the two, but shorter game times end up giving you more time to play, and more global players thrown into the queue.
Reason 3 - The game is more interesting
In casual play, it's kind of dumb knowing that a late game vayne will end your team, or that even if your whole team comp does good, their team comp literally rolls you by pressing R.

Reason 4 - Kills are more satisfying
People are complaining about snowballing, the game is literally ALL ABOUT snowballing?
If kills weren't worth as much, then we would see more cancer strategy's.

Reason 5 - Change is always good Just because you've played the game for 5+ years, where the matches went 30-40 minutes doesn't mean you can make the shots around here. League of legends is not your "TYPICAL" moba. The game is where it is because of the developers finely tuning the game, not because of the community.
Riot if they listened to EVERY SINGLE COMPLAINT - The game would be a boring farm fest until 40 minutes, 1 team fight and the match would end. Players would become bored and quit, indirectly losing profit and possibly the game.. ending for good.
Riot if they DEVELOPED their own ideas - The game keeps getting more and more interesting, we aren't watching tournaments of players farming minions. It's a PLAYER vs PLAYER GAME. Every new season with new changes, has been retaining the old playerbase and still caters to newer players. It's just the older players are more flexible than ever (why I can swap champions on the fly but you just feed)