Well, a lot of people want to get laid for all the wrong reasons.
Like trying to decide their selfworth based on how many chicks/guys they can score. Using others as masturbation tools is wrong too, unless the sex-partner is aware of and agreeing to interaction on those terms.
Why virginity is a big deal:
"Magical cups, bloody brides - virginity in context"
"20 Questions About Virginity"
and wiki is always shiny: