Because you have a complete misunderstanding of the coop dungeon. Its not like a wow raid where best gear is. The only thing locked behind it is cosmetics and a retemper scroll. And Im telling you this as a fellow solo player who hates raids and wont be touching that dungeon with a 20 foot pole. Unless you just GOT to have these cosmetics or desire another trip thru temperville with a piece of gear, you can ignore it.