Why aren't there bigger and better rewards for good behavior?

I'm sure I'm not the first person to say this, but why aren't there better rewards for good behavior? The Hextech loot system gives Riot a variety of ways to reward players, after all. Why aren't we getting random chests/keys for accumulating post-game honors? I wasn't playing when the honor initiative was introduced, but from what I've seen, most people don't seem to care much about it.

Positive reinforcement seems like it would help the game community's problem with toxicity. Warning players that they'll win fewer games and then banning them if they break the rules is a start, but it doesn't do much to help the victims of trolling and harassment. But if a would-be toxic player knows that they'll get some free skins/champs by playing nice and being positive, wouldn't that make everything much better? Sure, some cynical folks will act the part to get the loot, but that's good enough for their would-be victims, and surely some of those toxic individuals would realize that they're winning more and having more fun when they aren't telling somebody to kill themselves over a couple deaths.

Giving highly honored players an extra chest every so often shouldn't hurt Riot's bottom line by much, and surely they're already losing some amount of money over people who can't stand this community any more.