One last thing- although it sounds like I'm complaining a lot about it, I actually did enjoy combat in the game a lot. I wasn't ranting like AVGN while fighting battles in the later half, I really was enjoying myself even though I did yearn for more challenge. The system for this game did introduce a lot of new and original ideas to it which I do appreciate.
I'm something of a challenge-phile though.
My advice for dlc or an update would be to add in an optional "Extreme" difficulty option, complete with an achievement with those who play through the game entirely with it. Skyrim's one of my fave games for the ability to switch over to a wimpier combat skill set when things get too rough.
Toss in a few deliberately hard side-quests, etc., (maybe an "Emerald Weapon"-FF7 type boss?) call it an Extreme pack, and charge $1.99-$4.99 for it. And call the hardest difficulty "Infamous" difficulty.
The benefits of this would be it'd be a way of introducing new changes without having to be married to them for a whole game. You could see how well it works and how people respond to it, and use the data to make further decisions on how combat would operate in the sequel.