It's interesting how the initial question has derived from "negativity and violence" to "entertainment vs seriousness".
I ignored that one could find violence and negativity entertaining. In real life I rather thought that these things hurt people rather than entertain them
Actually I wondered about the opposite, that violence could be inherent to competitive tennis itself, I hadn't understood it was rather inherent to "entertainment".
This is a fundamental question I had wondered for long : here people are supposed to know tennis much better than me, as they probably practise tennis and play small competitions, which I don't ... and this is the result. Hence this question : was this violence just an image of the inherent violence inside this sport ? After all, many people have compared tennis with boxing, and the "bend over", "pigeons" ... comments seem to just be part of the tennis players' vocabulary. I thought it was a part of this sport which I actually missed completely because I didn't know this sport enough.
Now I read something different : no it's not the reason for that "MTF nature", it's rather that negativity and violence are "entertaining" in forums ... oh the joy and pleasure of the ACC and other trashing debates !
It's human nature, not tennis nature, thanks for this answer to my fundamental question.