The problem here is with people looking at this the wrong way.
Doing a dungeon has as an objective to farm fast tokens for some players, or get loot.
For some others (spiritbonding), the objective is to level up pieces of equipment to break down.
In both cases both are game objectives, I don't really see the difference. I've many times accepted to run a dungeon just to spiritbond (when I was close to decline because I didn't feel like doing it, or I got the tomes cap, or I don't need stones, or it is not my usual friends group - yes I spiritbond with them too).
I usually change gear on bosses (not that it matters much on performance from what I could see), because a boss seems to give the same spiritbonding exp than a trash mob anyway.
Side note: It is thanks to spiritbonders that you non-spiritbonders get to buy materia, and specially in reduced prices (unless you decide to go do FATEs specially to spiritbond, in this case I'll shut up, but I believe that's not the majority). The more spiritbonding there is, the cheaper the prices.
PS: I assume people posting this won't DARE running a dungeon with a class they have up to the level that is inferiorly geared or performing from any other they may have at the same level, even if they enjoy the playstyle more... that would be heresy!
