Most of your responses are addressing that directly. No need to set up stick men. (They're like straw men, only they at least have a little substance to them. ;)
As I said, all tight knit groups seem to face the problem of protecting wrong doers. I think this is worse when the groups, or sub-groups within the larger group have values which devalue certain groups. Those devalued groups become safe targets. You evidently know how difficult it is to force your own values onto a group.
Fraternities as single sex organizations set up women to be a devalued group, since they are already not members. Even if the Fraternity is founded with the value of equality of all men, even the female ones, the years when this was not the norm for Greek house, and the patriarchal bent to our society generally fight against it. And then there are the rapists.
College age rapists abound. They look the same as the average guy, mores the pity, as do those who would just look the other way and condone rape when done by someone they know. I know that there are many men who find either behavior inexplicable and abhorrent, but all too often I hear about and hear from the other kind. I have been shouted down and denounced for pushing the idea that positive verbal consent before an initial sexual encounter with someone would be a good idea.
Note: I was not saying it should be mandatory, just that it would be a good idea especially in light of Illinois law which states that lack of resistance does not constitute consent. But no, that is apparently an outrageous idea. Some have protested that they would never get laid if they did that. (Apparently they could not imagine that asking their partner if he or she was ready to have sex right now could ever be anything but a mood killer. Piss poor imaginations is what I think they have.)
I think that the motivation for hazing is similar to that of rape; there are those who enjoy it, whether just as a power game, or sexually it really doesn't matter. In the past, Fraternities have used hazing to tighten the group bond, and so now, even when there are Fraternities set against hazing, some will dredge up the practice once again. Because they can.
I don't have a solution for wrong doing done by close knit groups. One would hope the groups could promote positive values among its members, but this is not always easy. It is vital that we come up with an answer because although fraternities are not necessary, military, fire fighters, and police still are.
I will mention that, having married into (where "married into" is looser than having actually joined) a coed Greek society, I am impressed by what Greek life can be. As an undergrad, however, I saw the other side of what Greek life can be.
Don, if you know of any students who *would* like to start a chapter of a coed society (Alpha Delta Phi, obviously), and there is no current ADPhi fraternity chapter at Knox, let me know. The society is looking to expand, and I am friends with those in charge of the expansion.