the dungeon finder is a great tool. it's by no means perfect and of course by extension could use some improving. however, i would ask people who constantly complain about how terribad certain situations in these random dungeons can be, "it queued me for something i wasn't prepared for" "afk'rs in the group" "non tank tanks" and so on. understand that when you sign up for a random dungeon, using the dungeon tool, that braving these dangers, difficulties, and frustrations is PRECISELY what you signed up for, the reward of course being delicious frost badges (or more triumph badges). that is why they hand out the title "the patient"
most of the suggestions i see for how to "improve" the dungeon system are pretty double edged, and while they all make admirable efforts to address the more grievous problems, they usually end up weakening the whole thing in some other way.
basically i'm trying to say that many of you are expecting the dungeon finder to do something it really isn't designed to do. it's like using a hammer like a screwdriver, and then getting pissed off that all your screws are bent. perhaps you should change your expectations of the dungeon finder to be more in line with what it really does, and understand the limitations of the system, rather than expecting it to provide you with a group of 4 pleasant, competent people to have a good time running a dungeon not of your choosing. because while it is fortunate when that happens, it shouldn't be something you feel like needs to always be that way, or else there's some major flaw.