Instead of not taking showers, we should all take cold showers for many reasons.
You already mentioned the energy usage which is a problem.
Hot showers increase the relative humidity of the bathroom to 100 percent which is way too high. And that humidity means that you get a lot of condensation in the bathroom too. That is good only if you want the bathroom covered in mold.
If you take a hot shower that fogs up all the mirrors, you are censoring your own nakeyness. Please don’t do that.
I do not care if people shower daily. But people need to exercise daily. And after exercising, people need to shower. As a corollary, most of the time that people shower should be right after exercising. But after exercising, you are already warm, so the goal is to cool down. This means that everyone needs to take a cold shower.
Cold intolerance is a major problem. People need to get over it. People who can’t tolerate a little bit of cold probably are intolerant in other areas as well. They cannot go mountain climbing because the mountains have snow on them. They can’t tolerate hot peppers. And they are afraid of spiders too.
Whether one takes or should take a cold shower or not depends on a lot of factors including whether one exercises, one’s health, one’s personal preferences, the air temperature, the cold water temperature, the humidity level, and the hardness of the shower water. But it seems like most people can’t fathom taking a cold shower simply because they are cold intolerant even though cold showers have many benefits.
In addition to the practical benefits of cold showers, cold showers also may offer health benefits.
Cold showers could improve one’s immune system (though we should).
The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial—PMC
Cold showers may boost mood or alleviate depression.
Scientific Evidence-Based Effects of Hydrotherapy on Various Systems of the Body—PMC
Adapted cold shower as a potential treatment for depression—ScienceDirect
Cold showers could also improve circulation and metabolism.
Cold showers also offer other benefits.
I always use the exhaust fan. It is never powerful enough to reduce the humidity faster than a warm shower increases the humidity. I also lock the door when taking a shower, and I do not know why anyone would take a shower without locking the door. Opening the door while showering just makes the rest of the home humid as well, and we can’t have that.
I exercise daily, so out of habit, I always take a shower after I exercise, and most of my showers are after exercise. Even if I spend a few minutes cooling down after exercise, I need the shower to cool down even more, and by taking a warm shower, I cannot cool down as effectively, so I end up sweating after taking the shower. And I sometimes take my temperature after exercise and the shower and even after the shower, I tend to have a mouth temperature of 99.0 to 99.5 degrees Fahrenheit. I doubt that people who barely need to take a shower after exercising are doing much exercise or perhaps they are doing weights instead of cardio which produces less sweat, but in any case, I have never exercised and thought that I do not need a shower regardless of whether I am doing cardio, weights, or whatever.
Soap scum left over after taking a cold shower seems to be a problem for you and for you only.