I actually prefer that it the way it currently works right now. If you want to know a way to "prevent" it, you can tell them to take the shower/bath in the cue BEFORE they are done working out/jogging. They usually skip changing back to everyday if you fill up the action cue. As for the changing from pj's to something more appropriate to wear outdoors. That is less bothersome. It isn't realistic to just go out in pj's.
Agreed, I prefer the way it is currently. Perhaps something for the Sims team to consider adding into gameplay settings is the option to toggle sims auto changing clothes.
