From the standpoint of the average NA/EU player, the single most influential factor in bringing a job is whether you make your teammates' dps look better. Your personal dps is a distant second. As long as DRGs bring Piercing, they're going to be a must pick. Your BRD will make sure of that. The same is true for NIN and Trick for most groups, although I think that that's also a case of supply not quite meeting demand.

Personally, I think they should get rid of the Slashing and Piercing buffs, simply because they add nothing to gameplay, and your damage potential shouldn't hinge on forcing you to bring certain jobs (let's face it, it's not like you need to force players to bring a WAR, NIN, or DRG). Out of eight possible raid spots, four to five of those have almost always filled by the same jobs for nearly six years now. I think it's high time to shake things up.