There is one usage case, i can call - reversing recorded piano and some other instruments. One case, when sequencer and even instrument settings are not last step before mastering. I'm not expert and at all badly aware of existing music to mention examples, but i know at least one - in Black Mesa game - some soundtracks, marked as "mesa remix". I don't see it bad to mention such stuff there, since it is done completely by fans, no matter with what resources and software. Additionally, in gui clips may display inline status, with indicators for direction and all other clip-individual info, such as speed (probably, that's all - don't know, what other indicators are good to have there).