I dunno about the lack of melee gear. I suspect that argument is coming from melee priests who do not have access to a fabled 2h nor a full set of red adorned gear where the red adorns offset the lack of blue melee bonuses.
On your spec, I've never had much use for immunities. Are you just macroing it to cast on yourself everytime it's up for the extra immunity? I'm always wearing stun/stifle blocking procs and I'm usually grouped with an inq who has steadfast+epic. And if all that fails, I have the standard pots + bristlebane blessing. I could layer an immunities spam on that too, but it seems like overkill.