I actually have really bad opinion about healers who just stand there doing nothing in light healing situation. Sure they didn't choose to be healer to dps but standing there staring at mobs? Lol. I find most of those healers are not so good healer in general. Even if they're good at healing, I dislike lazy players anyway.

Most extremely good healers in raid can switch Cleric Stand like a boss in dungeon setting. The best one was a whm friend of mine who holy spam big pull then benediction tank just before he come down, give him a little bit of buff then back to holy spam. The dungeons that usually take 25 mins to complete only take 15 mins when I go with her.

Oh, if you ever farm King Mog HM, you will see the big difference between having a whm that holy at the beginning of phase 2 and having whm that don't.