I think they expect udder rubs for it because they consider calving to be a war and the physical destruction caused by pignancy and birth are their "battle scars" which people are only allowed to find beautiful because Moo sacrificed her former physical beauty in order to partake in the creation of life, which is the most beautiful thing ever. I just threw up in my mouth a little saying that.
I think they're just delusional. There is no possible way they genuinely find their new bodies at all attractive, let alone
more attractive than they were before. And I guarantee a vast majority of them don't look at their stretch marks and go, "Yes, my child was worth this." It's a defense mechanism - my Freudian psychology might be rusty, but I do believe that's called reaction formation, which is believing in the opposite of the truth in order to avoid having to face it.
They can't afford to get plastic surgery to fix that mess, they'll claim they don't have time for diets and exercise, and they sure can't give the brats back in exchange for their old bodies, but lying to themselves and telling people what their beauty standards ought to be is free! Plus you can bet anything they'll attack anyone who posts before and after photos of things like weight loss where they've actually improved their appearance. They'll be accused of being vain and wanting silly, trivial things like a nice body or good health. If the person in question is a woman, Moos will shoot them down by saying it's all for nothing and they'll lose their progress
when (not if) they breed or that they're being whores for flaunting their bodies and being proud of them.
If you're truly confident enough about your body, why do you need to share it in order to score compliments? They probably figure nobody will be ballsy enough to tell them their stomachs look like infected nutsacks and the only people who will comment are people praising them for their "beautiful" mommy goddess bodies. You can't share stuff (be it photos, stories, artwork, anything) and not expect some criticism. If you don't want someone saying mean things to you, then don't share things. I think some of these Moos are also just plain looking for a fight and sharing stuff that has a chance of earning them negative comments is the perfect vehicle for them to start an argument with someone.