The answer to your question is one of math. If your armor is reinforced enough, in the proper ways, then having 0 DCI wouldn't matter, even against a melee only opponent.
If you don't reinforce your armor but instead factor in that your healing skill can gain you X hp/second, it's still just a math problem, just with another term to resolve. If you fight things that do more damage with magic, then DCI will matter less.
It seems that most people suggest reinforcing Phy, Fire, Energy resists and sacrificing some DCI as is, so if you're already down at a max of 20 DCI, vs 45 (I think you can apply 5x enhancements to each armor piece) then going from 20 to 0 is not much of a big deal.