Mastery Tokens for other game modes

So I've been wondering this for some time now and came to the conclusion, why can you only get mastery tokens on Summoners Rift? I mean people don't just play league for SR anymore, the game has came a long way and has multiple maps and game modes now. With out this the people that play the other game modes have their effort wasted. I mean even Twisted Treeline doesn't and there's a ranked for it, this makes no sense. So why not adapt to the times since league has evolved and add mastery tokens to the other game modes?