I often use “Stop When Finished” mid-album, and would like to be able to just hit “Play” on my keyboard when I want to start listening again. However, this resumes at the track I just listened to.

As I recall, Quod Libet's implementation of Stop When Finished would leave the player paused at the very beginning of the following track. Having told Banshee to stop after the current track, there are basically two things you might want to do next: continue listening to the current queue, or listen to something else. In the former case, QL's behaviour is better; in the latter case, it's irrelevant.