How come we don't get more bans?
- the purpose of bans isn't to fix Riot's balance.
It's to ban a few champions you just don't want to fight against that game, a few champions that would mess up your team's strategy.
"OP" picks are overhyped in LoL. It's not like there's a valley between the weakest and strongest. The lowest monthly win-rate for a champion is still above 40%, highest doesn't get out of the 50s. You can also totally counter-pick OP champions with a lot of the sub-50% win-rate champions and do very well.
Not to mention a lot of the must pick/ban champions in worlds occasionally are one of those 43% win rate champions, and the top 4 champions this month overall weren't even picked or banned once in worlds.
Just saying - how do you know a champion is actually OP and not, like, 0.000000000000001% stronger then the next guy, simply being used cause he's slightly stronger? Said champion beat you that one time with a significant item and level advantage in a game where anyone with a significant itemization or level advantage will pretty much destroy you by default?
If Riot did give more bans to shore up their balance team's work, it also sends kind of an awkward message to the player base and balance team.
- More bans would mean a longer start to a game. Obviously a few bans wouldn't add up to much, but every little bit of waiting adds up - and the average game length is ~33 minutes for LoL.
Could be a pro or con concerning communicating with the rest of your team and ranked already does take a fair bit of time to get underway, but you could easily approach the commercials to showtime ratio with just a few minor additions to pre-game waiting, which would suck.
- Biggest reason not to have more bans is the act of Target Banning though.
Yes, SSW had players with massive champion pools, and every pro team tends to have at least 1 player with a solid number of champions.
But everyone else is mostly stuck with 2~3 they're at their Elo with, and maybe another ~2 flex-picks.
With 5 bans per team, it would be incredibly easy to target ban specific players, preventing a lot of pro players from ever playing or showcasing their signature champions.
With 4 bans you could actually ban out the signature champion of every player but 1, then pick that champion away from the last guy.
Also - it's important to consider the champion pools of the average player. There is a significant time investment LoL requires to get a decent sized roster up - and in ranked solo you might have to fill a position you don't main. It's pretty easy to ban out players pre-game by looking them up on LoL-King as-is, expand the number of bans to 4~5 per team and you dramatically increase the chance you can just ban out some poor guy by chance.
Not that more bans isn't without merit - with a large enough ban number you could force more pros to main more champions, and give more time to get to know your team pre-game.
OP champions is a pretty awful reason for more bans though. A band-aid solution at best.
Also, due to human nature and what I've seen from meta's in general, probably wouldn't have any impact on the perception of OP champions at all.