But that's just my opinion. What do you guys think?
Main issue with more bans is this: While the number of champions one can play has certainly increased, the amount of time it takes to master champions really has not. It generally takes 3040 games with a given champion to really main them: and periodic nerfs/buffs/item changes can dramatically change how a champion lanes, builds, trades, and team-fights requiring even more time to get the hang of.
As such: more bans increases the likely-hood of target-banning a certain person. While individuals certainly exist that are impossible to ban out even given 25+ bans against them, the vast majority of players competitive or otherwise tend to have a rather small pool of champions they do well with.
With enough games with a player picking an "OP" champion because they're available and proceeding to fail hardcore, it's also pretty clear target-banning a player so they play like that guy is going to significantly increase your chances of winning over pretending to be Riot's balance team as well.
More bans would place a lot of stress on players to diversify rather than perfecting their skills with there favorite champions, and forcing players to play a lot of champions they have ~eh levels of fun with rather than there favorite isn't the greatest. Sucks a lot of fun out of the game.
More bans also increases the amount of champions new players need to enter ranked for the first time (as you need enough to not be completely banned out to enter ranked).
Which sounds good initially until you realize getting to level 30 in the first place takes ~2 months with daily play, and ~1 month with no job/no school heavy play. A wide range of games on the market don't even require that level of investment to 100% complete, and yet LoL players are barred from the ranked experience even longer.
Making ranked an even more exclusive club is also really counter-intuitive when contemplating what ranked actually is: it's about ranking how good players are compared to one-another, not a place where good players hang out. And making the entry much more time consuming excludes more naturally talented players while still retaining a lot of unskilled players.
And with how champions are priced in the store: a 2 champion increase due to picks/bans is a substantial hike in the IP entrance fee, as you run out of all the 450 champions and need to branch out into more and more costly champions. If you're trying to learn a specific roll rather than running fill, it's probably 2 6300 champions just to enter ranked.
A higher IP demand for entrance to ranked also places a higher demand on IP farming bots and purchasable accounts, which isn't great.
Finally - most broken, OP, must pick/ban champions are only better than the next guy in line by 0.1% looking at their statistics and performance, even factoring in things like checking games vs. players with 40+ games on the champions they're playing.
The notion there's an exclusive club of ~~15 champions in total that are must pick/ban super-OP and giving 15 bans would make the game really balanced is complete BS.
All champions in LoL are on a really steady gradient of power. Ban the best guy? there's the 2nd best guy that does everything the best guy does but 0.5% worse. And a 3rd best that does everything the 2nd best does but 0.5% worse. And a 4th, and 5th, etc.
Giving more bans so the player-base can pretend they're the balance team just moves the arbitrary line of perception concerning who's OP and who's T_T never played.
Granted - there's occasionally 12 champions that Riot accidentally over-tunes that actually do have a huge lead on the next guy and really should be banned, but 6 bans has always been perfectly capable of dealing with those champions. Riot doesn't rework/release champions in large enough quantities to make that a percentage of the roster problem.
TLDR:
Increasing the number of bans isn't a kind of change that should be done lightly, doing so has it's fair share of cons.