It debases society, because the language children hear in a TV show (which they are going to watch regardless of the rating, because it is after all Star Trek) spoken by purportedly responsible and sophisticated adults is taken as acceptable and normal, and the children will emulate that language. So if Star Trek uses "F______g cool" as an expletive, and a second grader used the same expletive with her teacher in school when she gets a good grade, she can't be blamed for following the example she was shown. I mean if it's good enough for vaunted Starfleet, it's good enough for little girls, right? I just think we can set far better examples.
F__c is vulgar for copulation, and we don't teach second graders about that, do we? Should we? Shouldn't we afford them some childhood innocence? A Star Trek reboot more in the spirit of Roddenberry's original vision, versus recent alternative universe reboots, should be accessible to children as a hopeful future vision of humanity, without unnecessary adult aspects that make it unsuitable for their viewing. I know I'm hoping against hope in an ideal world that requires ever edgier content to compete commercially against other programming.
Also, while the word f__k can be used in passion in a respectful relationship, it is more commonly used when referring to the act in a base manner, without the aspect of love and unity and procreation that lovemaking is ideally more about. No doubt, many may regard this post as puritanical, but it's really more about advocating for human dignity and respect, and especially in the supposedly evolved Star Trek universe of higher sensibilities.