Can't I have both?

Larian doesn't quite have the same resources as BioWare.
Keeping the existing length and adding main plot branches would be nice, but personally I'd rather see the cut areas put back in than alternate plotlines. There was a swamp that got removed during development (screenshot 588KB), and an area containing elves and dwarves (possibly even the same map as the swamp), and FoV started out with a Broken Valley type area, which was cut as finishing it would have delayed the release by the better part of a year.
In Beyond Divinity there was a point during development where Larian considered dramatically restricting the main character's speech options simply due to the costs associated with localization.


I understand that this game was meant to be a glorified hack n slash with RPG elements

No, no it wasn't. Now, come here so I can slap you...


without forcing the user to really consider in depth choices that alter that session of the game.

Actually one of the early design goals was to have significant choices (see the old topic Moral dilemma's in RPGs, for example). In the side quests that didn't come across in practice as well as it could have, and of course a non-branching main plot can not reflect the consequences of earlier choices.

About your spoiler:
If there are guards or bandits around you can get help with that fight.
The guards at the front gate of the village in Broken Valley alter their speech several times in response to your actions (killing a demon and returning the claw brings praise, while summoning the creature creeps out one of them, etc).


However, a simple internal moral/faction/etc. counter could be implemented easy without huge story arcs.

That's true, but there is an argument for not doing something if you are not able to do it right. There was a reputation system in Divine Divinity and Beyond Divinity that influenced the default reaction of NPCs and trade prices. As long as your reputation didn't get too low, though (ie attacking friendly NPCs), it didn't have a huge impact on the game. It was nice in DD that guards would tell you to move along, etc, until your reputation improved, but when prioritizing features I wouldn't necessarily put that on the 'must have' list.