Party combat is the foundation of DA. I wouldn't want to see less enemies (what the OP is talking about) because some people feel they're inconvenient.
Oh I'd go further. Combat has been the foundation of just about every RPG I've ever played whether on computers or not. D & D really didn't even have "quests". "Questing" is a mechanic that's really kind of taken off in CRPGs (i.e., have discrete objective, finish discrete objective, get reward.) The only thing you got XP for was killing monsters. Period.
I'm not expecting this to change in Dragon Age. The developers have not tried to be innovative in this series with what I'm talking about; but there's no reason to be particularly critical of them here, as I don't really see anyone else doing it, either.
Combat will probably be essential to just about any genre. The only one I've noticed that does things a bit different are the comic-book based superhero RPGs. Like the comics, there isn't a lot of dying, not even of the villains, because they've got to return. That would include Freedom Force. Supervillains, true to the comics, are almost never "killed" - just apprehended. Their minions of course are also usually "KO'd" at 0 hit points instead of killed. Of course, it's all still fighting, it's just that supposedly no one's dying.
Of course, if you can think of many video games, period, which don't involve fighting, combat & killing - it's not a long list, is it? Oh yeah, the Sims. And we all know (stereotype incoming) "that's just for girls".
As I've said enough times, I do find the combat portion of these games interesting, as long as they are more like tactical wargaming and less like Space Invaders or Mortal Kombat. More thought, less action and twitching. Still, I'm waiting for the innovative developer who will not take out combat (I just don't see that happening) or even de-center it out of the game, but at least offer some occasional variety for people who occasionally want to find a resolution in ways that don't involve killing. Looks like the Vampires: Bloodlines folks tried it. Good for them. Like I said, yay innovation. Almost makes me wish I had tried it.
IMHO, gaming is about overcoming challenges; not always involving some form of shooting aliens. I think I've said that. A creative developer can put different challenges in your way to overcome, that are not of a military/combat nature. Not all the time, not even most of the time, but some of the time. I've used "politicking" as an example, like the Orlesian Ball thing people keep talking about, or being involved in real life diplomacy (not just talking diplomatically). It'd be cool to see it, as something to do besides conversations and killing. Once in a while.
Back to the real grief of the OP, IMHO, combat gets boring if it's repetitively facing the same mooks without any variety. I think this is what the people upset over "trash mobs" are ultimately getting at. If it feels the game is endlessly throwing the same faceless t-mobs at you with no distinctiveness and no 'personality' (by that in this case I mean interesting combat-based behavior or actions), it gets boring. The fun is lost. Challenge has once again become tedium. Endless battles of nook-minions can be tedious, too, as much as having to eat and drink every 4 hours.
Developers need to be better at that, at designing enemy encounters - at least. Not everything you fight has to be a Tremendous Boss Battle or for a Incredible Game Objective , but as I've said, it just gets tiring, boring, and tedious when you've been ambushed by the same uninteresting, bland, interchangeable bandits for the 800th time.