Given you want to improve at all and you notice that the lowest dungeons to run (MC and TR) take really, really long, I assume that you would stop and start to think at one point, about how you can improve your gameplay.
If you do, then you will start to look for information and get a grasp of what to do with your class, which includes looking for the correct rolls.
If you don't, then you will still be an exceptionally bad player by the time you can queue for FLNM.
I consider the instance matcher one of the main features of the game.
It was until we got cross server LFG, not anymore.
But still, since my philosophy (again) since day 1 is that someone has to help them (our noobs in this patch) to create ..the game being played and not a ...totally....dead game (lol).... yes sometimes I "suffer" for a bit and help and occasionally train a student for a bit and that sort of thing. Hopefully people helping each other has helped keep tera alive a little bit because Tera is sincerely a good game over all and worth 1 play through.
You aren't helping anyone just by using IM and doing very slow runs.
If someone isn't well equipped, then you can help them by running with them, or making their runs faster if you are equipped yourself.
However this is not the case here. You don't help players who lack understanding of their class by making their runs faster or carrying them. What you can do is teach them or provide the knowledge ressources, but this is only half as effective if you would need that help yourself to begin with.
But anyway friend you do you and I will do me. That's what games are for is having fun. I have fun by helping others and seeing them progress and learn.
If it's fun for you to do these runs, then I have no idea why you started to complain about runtime in the first place. But it is getting extremely dishonest if you use a run like this to proof a point that dungeon balancing would be bad, knowing that you are playing with exceptionally bad players to "help" them.