There's that saying "to each his own". I feel that if you want to wait you should, if not, then why bother.
Personally for me, I was having sex long before marriage. But I can understand some people waiting for religious reasons. As for STDs I never really understood that one.
I have one friend who waited until she was married, age 27. She said she never regretted it one bit, but hated that he had a lot more experience and it was intimidating. But she was happy with her choice and although I teased occasionally she teased me too (she'd call me a slut and I'd call her miss virgin lol) but she knew I respected her decision and supported her 100% even if some of her friends didn't.
I think it's just a personal choice