I'm a storyfag, a RP fag and I enjoy difficulty as well, would you figure that.
I don't enjoy mechanics made for people who can't control their frontline without help.
It's not really about not being able to control your own frontline, it's more about the enemies controlling/limiting your bum rush, to try, I think, to simulate that "battle line" thing for the AI, that was totally absent from IE games, and stabilizing the fights a bit. Sure you can still trick the AI and rush around to get the casters/archers/boss/whatnot, but engagement system makes it an actual difficult choice as it can be very risky if you try it unprepared. Sure you can cheese and whatnot, but who cares, cheese's gonna cheese anyway.
With or without engagement, I agree that the player could and would be able to control his own frontline, as it was possible in IE games. But here, unlike IE games, you sometimes NEED to clear all the damn frontliners in full plate of the AI before you can get to the grand prize. In IE games, you totally ignored everything, gibbed the boss/casters/whatnot cheesing through lines of fighters who couldn't do shit to stop you, then mop up. That made "tank" or any defender role COMPLETELY useless AI wise.
I won't deny that it does make the game easier though because the game has a lot of artificial difficulty due to the engagement mechanics. Might have to do some creature modding down the track or something to make up for it.
It's not really artificial though is it? Supply limit IS artificial, especially with unlimited stash (also completely artificial). But a system (with all it's flaws and whatnot) that tries to simulate this concept of it being hard to just run through everyone unhindered is actually, I think, not artificial at all. It's an abstraction in a sense, and might not be the best implemented system for it, but it does the job...well somewhat
Never tried without engagement system from the mod or whatever but I already know the effect because that's exactly what you do in your IWD videos and that was the problem for me with the IE games mechanics: complete cheesecake combats.