Since you like to compare League of Legends and DOTA2, how about we compare DOTA2 and DOTA.
From what I have seen thus far it has all the same champions, same MOBA game play and the only notable difference is the graphics. Honestly, why play DOTA2 over DOTA (other than it isn't on WC3)? Those exact reasons are why I see a lack of selling point in DOTA2, especially compared to League of Legends which is free to play and has multiple game modes.
Also, I think you are at why they are releasing Dominion in the wrong light. It is a new game mode, or rather a new flavor of MOBA. It keeps people interested and gives them something else to do other than SR, because frankly, who doesn't get bored of just the same old map/game mode every game?
INB4 Junior Member, I played the open beta, I just don't spend my time trolling the forums I spend it playing the game.