Dungeons back then were huge and FELT like dungeons. Hell, they were bigger than some raids. Instead of a straight point A to point B, all had multiple paths and numerous bosses and trash that could be skipped by simply taking an alternate pathway.
Of course there was bad as well. This mean't that you had to have the time to do them if you intended to clear. And wipes mean't VERY long runs since, unlike now, the game didn't save spots so you would rez inside the instance close to where you wiped. You had to make the entire run, which in instances like BrD, was a torment.