The Decent game engine was taken originally from Doom: the boardgame - an engine designed to imitate a video game. Think of Descent as an old school computer RPG, like Dragon Quest or something, and everything starts to click much more cleanly.
When I introduce my friends to it I relate it being like a board game version of Diablo. Hack and Slash but not roleplay, which is a disconnect some of them seem to have trouble with at first. Misguided expectations can ruin their experience with the game betimes.
A lot of the rules and meta-tactics don't make logical sense within the real world. At this point is when we rely on our suspension of disbelief for the sake of a balanced game experience and having fun without worrying too much about how something occurs.
One of the examples I seen was a player on the BGG forum complaining that in the advanced campaign having to injure your allies to wake them up during an ambush. To me, this is the result of player meta-gaming. Thematically the whole sleep effect is about giving the overlord the advantage. The players beating on each other first doing minimum possible damage to wake up is a solution towards mitigating that advantage.
With the treasure issue... there's already enough going on in that scenario. There isn't really any reason to make it overly complex unless you think you'll enjoy it more that way. Access to treasure is limited in many maps, and getting to it either requires the potential sacrifice of a runner, or a steady slash and grab on the way to it. Sometimes there's situations when the heroes get in, grab the treasure, pop the glyph and return to town before you can react, but thems the breaks. On top of that, there's no surety that each hero is going to get an ideal treasure in the first place. My heroes waste more time on swapping treasures back and forth than they do on anything else in the game. Except for one player... who loves to go to the shop all the damn time. lol Every time they hit a pile of coins it's like he wants to go buy something. Though that may be my own fault, the first time he played, every time he started building up a nice little gold pile, I'd kill him and he'd lose half of it haha.
As an aside, if your heroes are split up across the dungeon from each other... the overlord has a major advantage already.