Everyone finished the roll/passed on the legs first, so it was given away first. It went to you, thus negating your ability to take any other loot that week.

Doing it piece by piece would take forever. Just roll need on the pieces you want, and pass on the ones you don't. If you absolutely MUST have that chest piece? ONLY roll on the chest piece and hope for the best. With 8 items dropping per run, waiting out a timer for each one would be maddening, and wouldn't change much, and may make things worse because then there would be no priority system for things early in the loot order.