Simple, they're still evil, but less evil, by making them a place to do therapy like stuff.

One ankle exercise that helps with balance that people are taught to do if they sprain ankles is to just raise up on their toes and then go back down, and repeat this. If its to help with an ankle injury its generally done on one foot.

However, I've found, if you do this standing on both feet, while washing, then what it does is:
1. Give you propioceptive input.
2. Give you a particular sort of vestibular input.
3. Give you vestibular challenging to work on helping train your ability to balance (making it easier to balance in the long run by practicing in a situation that's just a little too hard)
4. Make you practice with crossing the midline (a thing that would be overlooked I think, but very clear from my tests)
5. Make you practice with identifying finding moving body parts.
6. Work on strengthening your legs and core; good for anyone with motor disorders, or with issues with balance, as core weakening tends to eventually come from too much issues with the vestibular sense even if it wasn't there originally

To increase the challenge, while washing one leg, just continue on the other leg. I am not capable of that at all. I also stop when washing my face, I cannot do the motor planning to understand where my face is when its moving even if my hands are moving at the same time.

To decrease the challenge, use an elbow, or a hand (if you have a way to do that without issues with soap) to balance against a wall. Just placing it against the wall lightly helps a lot with balance generally, and doing that at first isn't a problem. I actually leaned against the wall to wash one leg because this caused me to have issues balancing on one leg even while I wasn't moving, but standing on both legs I was fine. Depends on what your abilities are.

10 seconds of not doing this while showering and I'm nauseous. Do this and I can hold off the overload. My legs might hurt, but exercise pain is better than nausea.

Now I just need to figure out how to not want to chew my hands off, because now I really want to chew my hands off. I hate showers so much.