The problem with the golden key is you could easily get 2 pistols, 2 shields, heck even 2 class mods that arent your class. It'd be better if it was an exclusive chest which had say 1 shield, 2 different weapons, a nade mod, something like that, rather than potentially giving you something you've absolutely zero use for, and feel like you've waited for something potentially awesome and been cheated.
Last night i tried the player hack from BL1, basically scans the games memory, finds how many people are in your game, and you move a slider to however many you want the game to believe are playing, so you can technically knock it up a notch to make it harder, get slightly better loot, plus harder and more baddies to take out.
I went from end of PT1 done 2p co-op, to start of PT2 1p with 4p tweak, its a whole different game

Doing the very early mission from the first town to claptraps boat and back, killing Boom & Bewm on the way and then Captain Flynt at the ship, holy smokes, they're tough, cos they're 4 player difficulty (+PT2), with 1 person for them to target, and 1 person doing any damage.
Even same level bandits (w/ shield) were taking about 5-6 headshots with a very good elemental sniper (orange) (~2k damage, 400-500 element)
Mal X:
I think most people would disagree with you on Bulletstorm, its fun, but its considered a very average game for a casual gamer. Borderlands is still fun & casual but still works as a decent fps.
With BL2 you really have to look at items as a whole, not 1 or 2 stats. The best gun isnt simply the one with the most damage, you need to look at accuracy, capacity, reload time, elemental stats, plus any other 'gimmick' it might carry, like firing 2 shots, burst on focus/scope.
I mention this because the other items are similar, like your fire burst shield, theres a good half dozen basic types of shield flavours, whether its a standard shield, fire burst, or the others i wont spoil. Grenades too, there are nades which dont even require good aim, and understanding exactly what the benefits of each stat, and variation of a type of loot, is very important.
You could have a really high dmg/protection shield, but if it has a 5sec delay before it'll start to recover, once its depleted you've got to hide for a while before it even starts repairing, it could be 20sec before your back to full shield.
However on the opposite end of the scale, a low protection shield which takes 2sec to start repairing, a high repair rate, and its fully repaired in 10sec.
Likewise, using your playing style as a scenario, if your sniping, and they're shooting back from distance, when your sheild is dropped it lets out a fire burst... not really that relevant when your up in the hills or something, but if you were in the thick of it, SMG, Shotgun etc, then it's of better use.
Theres a very handy type of shield for snipers, i wont name it (unless you want me to), but it plays to those strengths you mention.
Thats the key to BL2 really, building a character around your playing style, and maintaining some variety because you may encounter something that doesnt suit your style, and you can either chip away, or switch weapon and find something that does more damage momentarily, then go back as you were.
Understanding the stats, and how to identify what makes a piece of loot good, great, or useless, is quite important.