First I'd like to make it clear, FM, that I have enormous respect for you and what you have contributed to this site. But I'm afraid I do strongly disagree, mainly when you say that this is a trivial issue.
The front page of the site is the first thing most people will see when they find it. I can say for certain that if I had seen the phrase 'family values' when I first looked at TTF, I would have been put off. I had already seen several sites that are overtly Christian in their approach. That's fine for them, but it's not right for me. I don't live in a nuclear family and I don't ever intend to. I think my way of life is just as valid as anyone else's. I live according to strong ethical principles but they are certainly not conservative ones.
I don't think this is just semantic hair-splitting. The phrase 'family values' is very strongly associated with conservative political movements, both in the UK and in the US. As I said before, I have nothing against people expressing these views on the forums, but I would not like people visiting the site for the first time to get the impression that it is the 'official' or dominant view, just in the same way that it would lose its inclusive quality if it appeared that, for example, anarchist politics was the dominant ideology.
I don't see why it would be such a big deal to have a slogan that is more politically neutral, that would reflect the way the actual forums have such a strong pluralist content and such an excellent level of mutual respect.
See, e.g.
Family values - Wikipedia, the free encyclopedia