I actually really like the marketing of not offering all champions directly, KNOWNING that you can acquire champions without money but with points you get from playing the game.
When you start playing LOL you have to choose from, I think 6 different champions? Which is pretty limited but let you master those 6 before changing them the next week to 6 new champions. I learned the game without problems this way.
DOTA2 let you play with all the champions directly, oh boy was I lost and still am 200hours of games later. I only play "random" so I can learn every hero but I still haven't played 25% of them I would guess.
Also I know many friends who bought champions on LoL, I think it's a very good source of income.