They have always pulled people out of coach, but it seems the ratio of those is far higher than it used to be.

In the old days, I think the computer did a run at 30 minutes prior - if you hadn't checked in, then your seat was given away - both as a first class pax (to upgrades) and as economy (to stand-bys). I think now, since they seem to be boarding flights earlier (security and all), they have revised the policy to keep people from standing around in the gate area. I guess I can see what the issues are, but it's still a lot less pleasant.