The one thing I really like about having a healer in the group is for one they can heal if you really need it and if you should have one of your toons die they can rez them right away instead of your entire team being on hold while you have to run that toon back to the group. You're going to have a toon die here and there from time to time either it may be dc's, afk, or you're trying something more difficult then maybe you should cuz it looks fun w/e one of you're toons will surely die at some point. Imo durning those times it's very nice to have a rezzer/healer.

But that's just my personal opinion. 8)