Right, the violence is worse because it's not consensual like the sex was. You make the fight consensual too and the sex becomes worse. Make them both non-consensual and the sex is still worse. The fact that the two sex partners were both consenting and the fighters were not is going to skew the answers to the poll. If you want to make a fair comparison you have to start from the same place and this analogy doesn't do that.
perfect answer. Although it depends on the context - one has to assume that the sex was likely premeditated while the consensual brawl was less so. If it's a sadomasochistic thing like Opebo suggested, then the public sex would probably be less deplorable since that would elevate the "fight" to the level of almost violent [but clothed] sex.
A consensual fight could be a drunken street brawl, gang violence, one man challenging another to a duel, etc.
Nothing wrong with sex in public, but one should probably be more discreet than a sidewalk.