this is after a finish of the match or after you win a very decisive point.
Not after every single point.
And they don't look at their coach like looking for approval.
Since you're honestly asking and the issue is making you jump to a lot of negative conclusion about some players' mindset, I'll take a crack at explaining this for you.
First of all, it's important to understand that people handle stress and anxiety differently. For some people, vocalizing and making noise is stress relief . People are wired differently. If it felt good for you to shout "cho-le" after every point won, you'd do it. The fact that you don't isn't something you chose or consciously decided. So you shouldn't feel proud of how you're naturally wired. Do you feel proud of the color of your hair or the length of your nose?
Why does it happen more in table tennis than other sports? This is my own theory but it's what makes sense to me. Table tennis points are incredibly short. Shorter than tennis or other racket sports. TT requires intense mental focus, and 90%+ of the time is spent thinking about point before, preparing for the next one. Because of the shortness of points, there's a huge mismatch for what you prepare your mind and body for versus how much effort you actually have to exert.
In many other sports you're constantly moving so your mind doesn't have time for a break, or you exert enough energy where you don't have enough excess that needs to be bled out before the next point. In table tennis, you're constantly prepared for a 20+ shot rally, but 80% of the time the point is over in just a couple. So you've got all this excess nervous energy built up that needs to be released before you can focus on the next point.
Putting it all together, and let's take Harimoto as an example since you posted this during a match and clearly have a huge problem with him:
First of all, Harimoto is the most polite player I've ever seen besides the celebration. I've never seen the guy fail to apologize for a net or edge ball, and he'll remember a net he nicked early in a point that went over 20 shots and will raise his hand at the end when most players would be celebrating. Guy has a photographic memory when it comes to finding things to apologize for later.
Why would a guy who is polite almost to a fault be screaming his head off after every point won? Well, first of all he's probably wired to feel good after doing it. It's cathartic and probably helps him reset to some sort of baseline after winning a point. Maybe it feels so good that it helps motivate him to win points and to stop point losing streaks.
We don't expend energy as humans on unnecessary things. There has to be a benefit to it. For some people, screaming to relieve frustration helps players move on from previous mistakes. The Lebrun brothers do this from time to time after being annnoyed by themselves. It maybe drowns out the negative self-talk happening in their heads.
Another thing to consider are cultural norms. Maybe Aussies and Americans have more free reign to be loud and boisterous in a lot of different areas in life, so relieiving stress during a TT match isnt necessary. For Harimoto, who seems shy and mild-mannered off the table, this is his only chance to be loud and emote. This might be helpful to his game since he can concentrate his emotional energy into his profession.
Finally, Harimoto has been the #1 player and hope for his country since he was a little kid. All that pressure others have put on him and he has put on himself is something none of us will ever understand. So his emotional regulation and mental wellbeing is likely a huge issue for him and the Japan team. If they've determined he's better off releasing some energy being Screamamoto, then it's likely a tactical decision to optimize his mentality.
To conclude, people are complicated. If you can spend some time trying to understand their mentality, rather than just jumping to negative conclusions about their bravery or sexuality through the lense of your own limited world-view, you'll probably be better off in your social life and general outlook on things.
