We have rules because a line has to be drawn somewhere. Wherever the line is drawn, people will go over it. If we moved the line further toward the "lighten up" area, some users would still go further. Why? Because they are used to it happening everywhere else and because so many people think they can win an argument/debate on the net by one-upping the other side.
The rules have been established, adapted and revised over the last 11+ years. You have been a member here for 3 months. If you prefer the childish insults, endless trolling and personal attacks, there are literally thousands and thousands of other sites out there that would greatly please you. If you choose to stay here and post, you will follow the rules.