I think they quieted a lot of criticism by not applying fees to elites, though I guess there's still a possibility of getting booked to a middle seat and having to wait for time windows to open to try to move to something better. Unfortunately the most common situation for that is high-demand flights booked relatively late, and in that situation the person is more likely to have paid a fare above the lowest one.

It'd seem that the main target would be infrequent flyers on long hauls. These people are probably the least experienced with online booking. If two travel together, one usually gets a middle seat anyway (unless it's a widebody with side rows for 2). Someone might try Coach Choice to avoid a situation where a party of 2 or more gets split to individual seats, but usually that happens mainly to standbys at the last minute. An individual might use it to get out of a middle seat or into an exit-row seat on a long flight, but how often are the infrequent flyers checking the seatmaps?