Totally agree here. I consider myself pretty well locked out of running a full Arc run because of this, there's a 50/50 chance of getting an add at the end boss that's immune to nature. I was able to get through Princess without tooo much trouble but the ~50's encounters are a bit simpler than the 70 encounters.

I've also considered building up the melee gear for such instances, if it's a simple fight then the 5x melee isn't unmanageable but you have to be able to see it coming so you can switch to the melee gear cause otherwise, even with a great weapon, the DPS is the suck. Plus, I have to build up that melee set of gear, /sigh. I don't even have good caster gear yet, let alone a whole other set.

Ah well, still love me some shaman.