I don’t understand what you’re saying about the rewind button. I mean, if something ‘goes wrong’ either you haven’t done the workout as-prescribed (and, to me, going back doesn’t remedy that), or you just end the workout and start over.
As for sim mode, you should already be able to turn off erg mode during workouts and do them in sim mode.
On the second point, I didn’t realize that (I always use erg mode). On the first point, I’ve never unclipped, but if I need to step off during a workout I just use the ‘pause’ button.
it was just an example, there are many other reasons for wanting to redo an interval, like real life happening but I know no good reason to skip one, yet we have forward button but no rewind button