Glad to see lots of people so far are agreeing with me on this. I made a debate up about this once on the TMF and all these people listed reasons why being single is awesome.
For me, it's just lonely and depressing. I can only take being in the company of friends for so long before it is just like "this sucks, I need an actual intimate relationship."
Human beings naturally desire intimacy even if they claim otherwise. Studies have also shown that people that have long-term relationships live much happier and healthier lives for the most part (obviously not everyone does in that case, but overall when compared to life long bachelors and bachelorettes).
What you should try to avoid is claim that liking being single is somehow unnatural or wrong, or something that people are bound to regret. This is the same sort of blatant self-justification as if a single person started to preach that people in relationships only give in to peer pressure and in their heart they would much rather be single.
There are people who benefit from the encouragement to take chances and try harder for relationships. That does not excuse being condescending towards those who don't.
There are really a hole lot of different lifestyles out there, and people who "go with the program" have an annoying tendency (I feel) to label alternatives abnormal. I have this female friend who decided that she does not want kids. Of course, all the obsessive diaper sniffers gang up on her telling her about what HER natural human experience shold be like. Really, I understand the draw of having a kid, I do. But if you decide that you want something else out of life, then no-one has the right to say that you are some sort of psycholigical wreck who's suppressing her NATURAL feeling to be what -THEY- are like.
So, yeah, if someone wants to be single, let them be. Just like they let you engage in your perversities.
It's a different matter that on a fetishist site more people are likely to be looking for love and only single because the scarcity of possible partners forces them to be. But that's just the demographics for this kind of place.
PS, I'm not saying that the thread starter fell into this mistake, but some of the comments implied something similar. I think it is important to realize that this perception is inherently unfair.