Hypothetically, what would everyone think of a melee caster for DRK? I keep reading that DRK should be fast and I can't logically understand why it needs to be fast, it's a heavily armored big sword wielding class.

Combo would be something like Hit>Big Swing Cast>Dark Magic Cast, AOE Hit>Dark Magic Cast. Delirium could then remove cast timers and give it a attack speed buff(since everyone wants it), something akin to Berserk's Guts.