The idea is nice. But, I think bringing cleric/healer is more important in MMORPG.
No group was going out to kill mobs without cleric in DAOC. Otherwise that was a dead group.
Yes, and cleric has AE spells, but that was dangerous for him to cast those spells (group heal for example) as mobs aggroed very often and tanks couldn't get aggro off him.
Cleric and paladin had rez spell also.
I donno the class system of DD2, so it is difficult to say will there be a variety of different classes ? If yes, then as a party member cleric is very important.