What is wrong with "Unexpected"? Well, let's imagine this:
Hoshi, while communicating with a race of aliens the ENT has met, becomes friendly and flirts with a male alien; she doesn't go any further - or so she thinks - because she considers it unprofessional and dangerous, but the alien convinces her to participate in a telepathic activity that involves playing in the sand with her hands. A little later, after they part ways with the aliens, she finds out, to her shock, that she is pregnant, even though she has no idea how this could have happened. It turns out that the alien impregnated her - the telepathic ritual was actually the aliens version of reproductive process, even though he never told her what it really was. Everyone on ENT finds it hilarious, Archer has to work hard to stop himself from laughing, while Reed throws a couple of remarks to the effect that Hoshi should have, um, controlled herself a bit more. The episode is a lighthearted comedy.
How do you like this story? Or do you find it creepy? If you do, then you should ask yourself why you didn't feel so before I changed the genders and substituted Hoshi for Trip. And that's what's really wrong with this episode.
It's amazing that Berman and Braga never realized they wrote rape into the episode and treated it as a comedy. But of course,
rape is OK when it's female on male.
Then there's the bad science again. Why do Trek series always get genetics and biology so horribly wrong? The way that the aliens in this episode procreate makes no sense at all. If the child only has the genetic material of the female (a cop-out in order to justify Trip not keeping the child), then it would be a genetic copy of her, which would defy the purpose of sexual reproduction...not to mention that all the members of the species would be female.
This review sums it up. "Why do the females have breast, if it's the male that grows the nipple?!"