Clearly, you're not a dps. Even checking the "join in progress" button I'm still stuck in df for 20 mins or more waiting, then I have at least five minutes of people like you dropping out of the que because they only have to wait a minute or two to find another party. I'm in full support for a ban timer for drop outs. It already takes too long for dps to get into a lot of dungeons and people like you are a big part of that reason.
Dividing the spoils between each boss evenly would have as many negatives as it would positives. You wouldn't have as many people looking to fill groups, only those who need specific loot from specific bosses, but that would also mean more people would be queing for a fresh run, which in turn would make it take longer for dps who need early loot to find a party for the fact that there are only so many of each instance that can be open at a time and the line for parties trying to start in common places like CT would only grow in size. Putting a ban timer on people dropping and requing over and over would solve this problem without such negatives.
I play both healer and dps, btw, so I know from first hand experience how large the wait timer gap is between dps and healers. People looking to argue my point can skip that part of their argument. As for the "play with friends" comments, that's great if you're one of those guys in an fc of 300 or so people when you always have someone online to play with, or spend your days at home in your mom's basement gaming with friends, but a lot of people don't have friends who are online at all hours. Often times when I want to play over lunch or something, I don't have anyone to play with because most of my fc/friends/ls are in school, at work, or offline for other reasons.
This thread isn't about people leaving the roster while inside the dungeon, it's about people dropping out of the roster while the df is doing its readiness check. You would not be affected by this suggestion at all since you would already be inside the dungeon in this scenario.