I'd like to bring up a few points, if I may say so.
I would assume most men here have seen a semi-nude woman or women. Most men find the female body attractive, I think we can all agree on that. It's just one of those things Nature has endowed men with to ensure survival of the species and to ensure men continue to procreate. I would guess elk probably bugle to each other with some from of "Did you see the haunches on that cow?! Wa-hoo!!" It's a natural thing. Some here may not believe humans are animals or that evolution plays its little part in survival of species. However, we do not all follow the same moral taboos and codes. So, the point is, how do we all get along?
Now, in modern America, we have seen the rise of what is termed "political correctness". A machine shop that once had tool company calenders with semi-nude women on them suddenly gets a female receptionist whois "offended" by them and bam, the shop gets sued for "sexual harrassment". In other words, men are punished for being, well, men. On the one hand, here are some women who go well out of their way to be attractive to men amd then some go well out of their way to try and legally punish men for the "crime" of asking if they'd like to go out for dinner. It sends mixed signals and some men are confused as to what they can and cannot do. So, in many cases, men that find themselves in the company of other men want to act like men. I'm not saying all men have pictures of semi-nude women all over the place, I'm saying that it is a natural urge for some men to do this.
Now, in some places, people are offended by the display of the American flag. Others are offended by the display of firearms. How many schools now will not allow even allow school mascots that are frontiersmen or cowboys to hold "weapons" due to "zero tolerance" policies? What we are seeing is "being offended" running amok. The Bill of Rights does not guarantee anyone the right to not be offended. But, now we see making "hate speech" a crime looming over the horizon and, in some nations, it already is. My point here is that if one person is offended by the pin-up avatars, next, someone will be offended by the Magen David avatar because it's a symbol of "Zionist oppression" (Note: I don't believe that myself; I support Israel 100%. I am just stating this as an example.) Then someone will be offended by something else. This is what has happened in our own nation, America, right here. Kids can't read Tom Sawyer or Huck Finn because someone was "offended" by a certain word in those books. So, an entire section of American literature became off limits because someone was "offended". Well, sometimes, free thought and speech is protecting what is repugnant to us.
Another point is, this is a private forum. If this was a forum grade schoolers used in their studies, paid for with tax dollars, that would be one thing. But it's not. People must follow the rules of the owners. But as long as the rules are not broken, the exchange of ideas, even those we may not agree with or like, I don't see the point in initiating a PC censorship campaign that will only snowball until everyone is equally offended. I mean, after all, look how many disagree over Cold Steel!

Imagine if someone said, "I'm personally offended because I like Cold Steel and you said they're POS so I want your post deleted!" These things escalate. One person is offended by the pin-ups, someone else says, hey, now that I think about it, I'm offended by the display of "Pagan" images, another says he wants all references to Christianity removed. See what happens? Then everyone is too busy finding a stalking horse to use as a gambit to enforce his own personal agenda rather than talking knives.
The way I see it, the "hide" feature for the avatars is the solution. I understand why some people are offended by those avatars due to their moral beliefs and religious beliefs. I respect their beliefs. But I would also think that there would be mutual respect for those who do not follow those particular religious taboos. In other words, let's not call for a Sharia that all must adhere to, whether they believe in the God who set forth those taboos or not. Use the "hide" function. That way, all beliefs are respected as best as possible.