As you said, I think that TSA is trying to reeducate people on wait times. Most of the times I've been through Terminal A, all lanes have been open. The last time I was there about a month ago they were using the backscatter in the far left lane facing the checkpoint. I usually come in via the premium lane to the TDC - never is never anyone in this line, and I get into the far right lane.

Were they randomly selecting people to go through the xray scanner, or did you have a choice for the 'faster' alternative versus the WTMD? I say I prefer the case where there's still a self-selecting option to avoid an "OPT-OUT! Male assist!" shout out on their com system, but then this avoids a teachable moment to the people behind you if the TSO is asking why you're opting out.