Well done. Now, stick to it.
I mean it. While there's no such thing as "voting with your wallet" (no matter where and when you live--even if your local economics revolve around capital and even if your local governments are democratic), there is no denying that LoL is as good (or terrible) as it is because people keep giving Riot/TenCent money. (I've seen limited evidence that their big decisions are informed by something beyond their bottom line. Still, I'm not holding my breath for anything more.)
Addendum: Nevermind that Riot is dependent on revenues from e-sports, the corresponding risk for which is mostly borne by the players themselves (Riot itself bears practically zero). This would be the case irrespective of what individual players decided to do.
That doesn't mean that you shouldn't quit League of Legends. It just means that the effect of your quitting will only contribute to the improvement of League as part of a larger trend [of people quitting League].
(OTOH, I've read Rioters making the case that "this is the lifecycle of a massively multiplayer game." In other words, "as it gets older, it starts to suck, and people stop wanting to play it, and it eventually dies out gracefully [according to whatever progression earns TenCent at least as much as TenCent ever expected, if everything works as TenCent expects it to work].)
