I remember (kind of fondly, cause it actually went well) a DRK about two months ago that I got during 50/60 roulette who had less HP than I did on WHM in the Antitower. His gear was not broken.

Thankfully that dungeon is easy enough that I was able to tank it for him with the stunlock from Holy. He was super cool about it and promised to go gear up right after.

I know not everyone is as agreeable, my two cents are just to give people in crap gear a shot if you want to have them improve. Votekicking someone isn't likely to make them think about upgrading their gear. Telling them about the importance of gearing up while helping them might.

All that aside I would much prefer a blanket ilvl minimum for dungeons of certain levels as has been suggested here - forcing people to gear up to access content is really the only surefire way to make them get the picture.