I have actually asked agents not to put those on sometimes! Invariably, my luggage will be the last ones of the plane whenever the tags are on. NW could do better with this and it is a nice way to acknowledge elite status with just a bit of logistics.

This was discussed somewhere a while ago (maybe on airliners.net). It seems that because the way planes are loaded it is difficult to separate priority luggage from the rest of them. I know that AC does it quite well by loading the priority luggage either in a separate compartment or last. They are always removed first and dealt with right away.