Denying was part of dota aswell and Riot didn't port it over, also a reason why LoL is an awesome fail for me. Anyway, without last hitting it becomes a bit boring though after all the most important part of a game is PvP anyway, so it may work without having it as important mechanic.
We'll see, they are far from being done with the game anyway and usually most games Blizzard takes their hands on, are quite good. Though of course Diablo 3 was a fail and the latest WoW addons as well, they simply went too casual.