Hmmm....I orgasm easily and don't generally have a problem getting there via just regular sex. Not that every person I've been with has been able to do that, but I'd encountered some extremely boring guys. One of my dearest friends sleeps with insanely large #'s of people and has never had an orgasm. Not even from herself. She's 24, been with more people that I've probably ever met, and has never once had one. Maybe I'm just lucky?
Oh, but I can say that if I'm with someone and I feel like there's some big pressure to make me O, it makes me feel really stressed out and that's not a sexy feeling at all. Just my 2 cents.