...Actually if this was enforced in some way you would find a lot less people willing to run CT. I know I don't need some of the equipment, but I want to complete my sets of armor if possible. Call me completionist.
Additionally, I have some jobs around 40 that I want geared asap while running other jobs- I shouldn't have to explain why I want something or have to argue about it. If I want it, I greed and that should be end of story.

The point is, if you actually do indeed NEED a specific item to the point of tears and frustrations then you should run the dungeon/whatever as that job. If you can't (due to iLVL etc), then you're left at the whim of others, or you can gear up that job.