Play it with mouse and keyboard and dont use the mark target, its just better that way, they should make ranged heroes without any target lock system or autoaim like marking an enemy in WOW when playing a caster or hunter, its plain boring, however melee heroes should be able to use it, but it shouldnt be locked on to the abilities, there should be a skill behind getting the abilities to hit the enemy, but being able to lock ur camera on a certain enemy as a melee hero is one thing but IMO u should still be punished if you buttonmash and should be able to miss, the weapons shouldnt be the ones that are locked, but the camera or just the head of the melee character, making it easier for controller players to follow the one you are dueling, but this aint an mmorpg it shouldnt be autoaim on ranged abilities neither on melee weapons, only on camera/headmovement, so you have to adjust while fighting. Like in WOW you can target an enemy but if ur a rogue fighting another character close quarter combat and you run around eachothers in circles then it you should also be missing ur hits if ur not looking straight at the character and adjusting your line of sight, the game should do it for you.
It aint that hard to play good without autoaim on a controller.