If DPS was sleeping the mobs I assume you had a BLM. They have an aoe sleep and this may be why they told you not to sleep the mobs. Crowd control is great in lower level dungeons. I've use it to keep my party alive, especially when someone accidentally aggros a second pack of mobs.

I've done some dps in CC but quite frankly I usually don't have time in lower level dungeons. Most parties are not overgeared for content at those levels and need the healing support.