Most all of us have learned that certain things are simply unacceptable. We no longer have much tolerance for racially-motivated violence. We no longer think it reasonable that some people can enslave others. There is no tolerance for violent religious persecution. So far as I know, pedophilia has been rejected as acceptable behavior for hundreds, if not thousands, of years.
I suppose at some point in history, it was felt that institutional slavery, and attacks on other races or religions were just part of "human nature". That nothing could ever be done about those things because we humans are flawed and beyond any redemption. So there would be no point to trying to eliminate such evil acts.
Nevertheless, a horrible civil war was waged in the USA that ultimately eliminated overt slavery as an acceptable institution in this nation. Most nations around the world have, indeed, outlawed slavery - how well this is enforced is another issue. Here in the USA, numerous laws to eradicate racial discrimination have been enacted, and the descendants of the freed slaves are now protected by law from the sorts of evil that had been perpetrated on them during the post-Civil War period. Again, enforcement of these laws can be problematic, but the vast majority of Americans now reject racism as an institution. Persecution and discrimination against jews (and other minority faiths) have been rejected by most reasonable people in the USA. Atheist continue to be vilified and hated by many Americans, so there is work to do on that score.
My main point here is that the "human nature" argument is fundamentally flawed. Humans are not entirely driven by self-centered instincts. We can choose to disengage from those behaviors we see as immoral and evil. But such choices must be made one person at a time. Events might stimulate large numbers of people to repudiate a particular immoral action, but each individual human being still must come to conclude that some aspect of their character must change. Laws can be passed (usually when most people already have accepted some change) but no one other than the person can change his/her own mind. We often resist changing our mind just because someone else thinks we should, in fact! This can be considered "legislating morality" - a notoriously unsuccessful thing to try.
The key is our collective attitude toward something. If most people feel that some behavior is unacceptable, then legislation can be passed by majority rule, subject to scrutiny regarding its constitutionality. So you have to ask - do most Americans actually favor bullying, gang rape, violence on the basic of sexual orientation, sexual assault in the military, etc.? Is that who we really are?
When it comes to bullying, gang rape by athletes, or violence against people because of their sexual orientation, these will continue to occur so long as people continue to believe that such acts are more or less "harmless". Yes, the victims of bullying, gang rape, or discriminatory violence can survive and may even go on to prosper. But ask the victims what they think about such things, and I'm pretty sure they don't consider what happened to them harmless. For some victims of such things, their lives are damaged forever and perhaps even destroyed, and a few of them commit suicide eventually. Is that harmless?
So when are we going to start doing something serious about bullying, gang rapes, and other evil violence? Spineless, willfully ignorant school administrators don't want to get involved in battles between families (the bullies, the rapist jocks, they have parents, too, who always believe their children are veritable saints). There seems to be a "let things work themselves out" attitude, and that such violence is inevitable.
If pedophilia is inevitable, does that suggest we should ignore it? Should we ignore religious and racial discrimination? Should we ignore slavery, if it were to arise again? If you give up a just cause using the "human nature" argument, you're simply allowing the evil to continue unabated! You become part of the problem! How much longer will we continue to tolerate these things? Are we willing simply to let immoral, evil behavior go unchallenged? Remember the words of Edmund Burke: