Borderlands 2 And Bad Mission Design

My daughter Erin has mostly stopped playing Borderlands 2 with me, and it may be time for me to take a break.  This is because the mission design of Borderlands 2 is pretty damned dreadful, and the skill tree is a disappointment.
Now, the core run-n-gun gameplay is fun, which partially saves it.  But each mission you can take is long – I’d estimate at least an hour to two hours for each one, assuming you’re mildly incompetent, as we are.  And it’s long in the same way, in that most missions involve you fighting your way through a bunch of enemies to find the foozle.
There’s gotta be some study for “ideal mission length” that Diablo uses to entrap people’s souls, but Borderlands misses the mark.  See, when the missions get to be that long, you forget what the point of them is.  Sure, there’s a lot of clever writing about how you’re trying to hunt down a broadcast radio or rescue an innocent or deliver a fire cultist to the immolation pit… but when you’ve spent the last forty-five minutes repeatedly shooting and running and taking cover and hiding, you forget all that.  The flavor drains away, and you’re enmeshed in the same stupid gameplay mechanics, fighting your way to the blue rectangle on the map.  I can’t count the number of times I finally reached the goal and forgot why I was supposed to be there.
So what’s left is the mechanics.  “Oh, here I am, shooting again.  Just like I was an hour ago.”
Plus, the goals are often these absurdly padded multi-part extravaganzas: hey, don’t just kill one mutated vorkid in an annoying acid-melting fight, fight four of them!  Don’t just have one part to this tea party mission, have five of them!  And of course, you get no XP until you’ve eaten every last one of your vegetables.
It might help a little if the levelling up was more rewarding, but too many of the skills are passive (and thus easily forgotten), like “reloading faster after you kill an enemy.”  It doesn’t really seem like you’re reloading faster.  There’s no graphical doodad to remind you that this +15% speed boost is, in fact, a reward, so it just feels like you’re the same old guy.  And then half the skill tree things have multiple levels, so levelling up has zero excitement – what am I doing for the next five levels?  Well, I guess I’m maxing out this skill.
It’s a good game at the core, but it’s the little things that are fucking killing it.  If they’d had twenty-minute missions, then it would feel flavorful, like I’m making constant progress.  I’d be addicted.  As it is, I’m thinking of taking a break, and Erin already has.