I was bored at work and found myself thinking about DA2. I had an epiphany: the encounter design isn't the problem with the combat. The problem is that someone--hi Mike!--made the decision that DA2 needed to be AWESOME! In order for the game to be AWESOME! our heroes need to be AWESOME!ly powerful. Thus, a substantial proportion of enemies can be one or two shotted by a substantial proportion of our AWESOME! abilities--there's little short of a miniboss that can survive a whirlwind/spirit pulse combo from Fenris, at least on normal. If memory serves, this is true of hard as well (I think the primary difference is that your characters become less durable as you up the difficulty?). Which means, if all the enemies started in the same spot, you could kill or severely wound the majority of them using a single character's AoE attacks. And you have four characters, all of which can develop AWESOME! AoE abilities. Well, maybe not Aveline. She's not AWESOME!
So. If reinforcement waves spawned in sane places, and together, every encounter would go like this: Fenris walks up, uses AWESOME!singletargetstrike on the beefiest enemy, followed by whirlwind and maybe spirit pulse. First wave is now dead, except for maybe archers off in the wings. Second wave spawns, Bethany makes them eat a fireball and then a firestorm, so they're all dead now . Third wave spawns, Merril pops Tempest and chain lighting, now they're dead too, battle is over, ten seconds have passed.
I exaggerate slightly, but only slightly. Make sense to anyone?