Bump pics from mommies in underwear

Am I the only one really bothered by this? 
I mean, the fact that there is a growing baby in my tummy is an amazing, beautiful thing, something to be celebrated, but why would I photograph myself in a bra and panties? 
Would you post a photo of yourself in underwear on a random worldwide forum if you *weren't* pregnant? I'd think not (although I could be wrong about that too), so why does the fact that you're pregnant make it any more tasteful or advisable?
Maybe I'm just weirdly puritanical, but it really makes me wonder why anyone would do it. I can only imagine it's because they feel nicely hidden behind their profile.
There's nothing to stop these pics from ending up on dodgy porn sites, except a false assumption that everyone here is genuinely an expectant parent.