Regardless of what you do in any MMO you're going to have to wait a certain amount of time. The only time where you do not have to wait to do content is if you already have a party of 4 people. They already resolved the issue of reserving an instance, so now the only wait time is waiting on actual people to play the game with you. SE can't do anything about that. If 90% of the tanks want to do a premade party with their FC/LS then that leaves even less tanks that queue up for the DF. The roulette has helped a little bit in this by giving those tanks and healers that mostly run things in premades incentives to running in DF.

If SE made everything soloable, you might as well be playing a stand alone rpg. You can't do anything about the people trolling groups in DF, if someone decides that they no longer have time to do a dungeon when the acceptance pops and they declined, nothing can be done about that. I've waited for 30+ minutes on my DRG and while doing other things forgot that I queued up and when it finally pops had to decline because I no longer had time to run it. All that happens there if a dps declines is you stay at the front of the line for another dps, same thing if a tank declines, you don't get sent to the back, you just have to wait for another tank to queue up.