As for ways to make combat more engaging besides add kite/mez would probably "IMO" be more damage nerf across the board(the world is to easy to solo and needs more danger to me) and make boss mobs (especially in dungeons) power moves more devastating to make rage management a higher priority. Also saving achieving extra lvls for battle skills at launch for when you hit the 100 cap or only allow so many as you lvl will make people less OP while going threw the lower lvl group dungeons.
The world isn't "too easy to solo and needs more danger". The enemy strength vs the characters are just fine.
Of course, if you go to Eltibule at lvl 30 and Kur at 50, things might feel that way.
If you're a veteran who knows what abilities to get mods for, or even which of the abilities in a skill work best together, the game becomes a lot easier. But it's not the case initially.

It doesn't have much to do with how much players deal either, those numbers only have to be in balance among the skills. What needs to be done is more mob HP, while lowering mob damage output. And that's only for elite mobs and some bosses in dungeons.
Solo content outdoors is just fine. The classes with their cooldowns work well.

Making a build that can defeat a hard opponent is awesome and fun, making a build that can beat said opponent then losing anyways because you simply lose the dps check isn't much fun. Also once you get all your shiny new stuff combat becomes tedious and boring in it's current form. Then the inventory management after combat is also tedious, then a few vendors run out of cash so you have to travel halfway across the world to sell stuff and that's tedious, then you level up a skill but oh guess what....you need favor and cash for the unlock, more tedium...it's just too much, combat is one of the main places where it could be spiced up.
This is the main problem in this game, everything is such a pain in the ass, and sometimes for no good reason. I don't think nerfing damage is the best way to get it right.
- Getting rid of the "total respawn" mechanic is a good way, make mobs come back one by one.
- The shout mechanics are nice for some mobs, but for others, I don't know why they're even there. Wolves hunt in packs, but panthers? Social aggro should be restricted to social mobs, not to everything of the same sort or sometimes, everything in range.
- Dragging fights out by raising mob HP, while simultaneously lowering power costs of all abilities would make fights longer (and therefore more prone to mistakes, which makes them more difficult by default). You can then either tone mob damage down or shorten heal cooldowns.

In fights right now, it's not a lack of balance that ruins it, it's that you have to rush forward, respawns breathing down your neck, a lack of a proper resurrection spell and at lower levels (the 20s would be nice, to support grouping for dungeons at appropriate levels). Pets rushing in and pulling additional mobs is a pain.

The shout mechanic also doesn't make sense in some situations. Like when you want to pull, say, the mob in the middle first for strategic reasons, but can't get it to aggro by proximity without pulling something else, too, so you mez the mob that's in the way - now the mob shouts and they all come. Mez puts a mob to sleep and shouldn't lead to a shout, only damage should.

Then we have mob spawn design problems, like the first intersection in Wolf Cave, with a stream of mobs patrolling through, which is the most difficult part of the dungeon right at the start. Another example would be Kur Tower, where you have those large packs of zombies, melee skeletons and skeleton mages. Once you break through those places, it gets easier, when I'd anticipate a dungeon to start easy and then gradually get harder. Right now it's, if you can do the entrance, you're fine for all the trash.