How often do you think a vanity player should gear up progression players with no rewards?
How often is it ok for a vanity player to decide they're sick of not getting rewards and drop the group if they notice someone is undergeared?
Should undergeared players group together, and overgeared players group together, so that everyone in each group has the right to earn rewards for the dungeon run?

The "problem" only happens when geared people mix with undergeared people. Do you think the community should segregate so that everyone can roll on gear?

I think it's better to the mix geared and undergeared, and reward each by letting them need for progress or vanity. Undergeared players get powerful teammates while earning rewards, and geared players can help others while earning rewards. Both can run the dungeon again if they don't get what they want, and the community intermingles, instead of segregating.