You mean Sunken Temple? People still get lost in BRD, the fact that it's divided only added to confusion. I play this game since 2005 and still have no idea how to get from cell blocks to living quarters.
As for the leveling dungeons. I leveled 9 characters in dungeons back to back in WoD. There are only 2 problems. Wrath dungeon level distribution (only 2 dungeons 68-72), Queue times at Vanilla/BC, Wrath/Cata cutoffs, healers all go to the next expansion at 58, 68, meanwhile DPS sits in long queues for LBRS/Halls of Lightning.
All this "Everything dies too fast, I don't have time for my dots to tick" is not a leveling dungeon problem, it is an overarching game system problem. And it is addressed at the max level via affixes in M+.