RIOT doesn't want to make a fun game
TL; DR League is built around competitiveness and not fun. League is anti-fun (which isn't necessarily a bad thing).
Now don't assume I'm just some salty "I hate RIOT because I died in a game" fuckers. I love league and have been playing since season 4.
Now, I recently started playing Overwatch and came to a realization about RIOT's way of making league. RIOT isn't focusing on fun. I can honestly say that I do not have fun playing league. My attitude (and the attitude of most people) towards League is a competitive one. Even in normals, I still find myself try-harding and being pissed off when I lose.
When I play Overwatch, I find myself having fun each game. In addition to having fun, it still fulfills my need for competitive environments. Overwatch is simple in its objective so it rewards skillful plays and not tedious and complex interactions between each part of the map (league does this). RIOT isn't shaping league around being fun, they're shaping a game around being solely competitive.
If you don't believe me; Long game times where every mistake could cause you to have to play on the defensive for the rest of the game. Lots of objectives or different win conditions make it much more difficult to formulate a game-plan. With so many champions and changes every patch, META-gaming is promoted.
I'm also not a pro-player. I don't intend on ever being much higher than maybe gold tier. This game caters to everyone being "The best of the best 10/10 IGN new trick2g" when in reality; maybe 2 of us will be.