I always try to help people do dungeons as a healer or tank (join party in progress) but every time i get there, its just 1 other person, and even if the dungeon timer is full, i can wait the whole timer, and no healer/tank (which ever im not) will show up.

It's just a waste of time, for those that had to wait a long time to enter a dungeon, to only enter with 1-2 people inside.
You just go back to your queue, but now at the back of the line.

So I agree the timer does need to stop for 4 man dungeons (not for 8 man dungeons, since u get 2 tanks and 2 healers. Unless the group drops to 3 people or something)