I'm not very sexually experienced. I only had it a dozen times, and only with one partner. So it hard for me to get a clear image about how I feel about the matter. Therefor I might feel different about this, if/when I get more experienced.
Anyway how important sex is differs from person to person, but I do think it says quiet a big deal about a person if he/she is on an extreme. Like never had sex (and being in your twenties) or frequently having more then 1 sexual partner in a week. I think both can say a lot about a persons confidence, and how he/she stands in life. It alone can't give a proper picture, a virgin in his/her twenties can either be very confident and secure about him/herself or the exact opisent, the same applies with the overly sexual active person.
For me sex should never be a goal, but a mean to enrichen the experience you have due having met the person you're having sex with. It's a bit hard to explain, but I feel you only should have sex if both you and your partner(s) (I'm open to anything except humilation) experience more personal growth due to eachother then when you wouldn't have had sex. This requirement could be fullfilled in a onenight stand as well in a long lasting relation.
Though I can very well imagine that you and your partner just have sex because you both want it, especially if you're already in a steady relationship with said partner.
As I final not I want to say, that I find it rather pathetic, anoying, and demeaning towards women(because lets face it only men do this) to complain about not getting any. If you're bothered so much by it, then fix it! And yes this ought to be as easy to be done as to be said. I personally found that all social interactions are rather easy when you just get over your own petty emotions.