Last week I had all three sets for Brayflox nearly completed. The only thing I lacked were the tanking and dps chestpieces, which drop from the last boss. I spent basically two entire evening queuing for parties in progress. It was pretty much always instanta pop - sometimes 0/4 complete, sometimes 1/4 or 2/4, and very occasionally 3/4. But I ran them all. There are a LOT of bad and/or inexperienced tanks out there.

By joining partially completed runs, I was able to get the gear I needed faster, and groups were saved from having to disband and requeue. Is this open to abuse? Sure. But for every person who abuses this, I like to think that there's at least one person using it as intended. Tanks and healers already rarely queue for groups in progress, so I'm not sure it's a wise idea to give them any less incentive to do so.