I don't know where you live, but it's certainly not very similar to anywhere I've lived. Embarassing? Maybe for some. Shameful, no. I've never heard of or seen anyone suggest that sex is shameful in any way. Maybe some prudes think so, but it's not "widely thought".
There's nothing wrong with any two consenting people of sufficient emotional maturity expressing their sexuality to one another. When you get these kids treating sexual acts as a commodity, a thing that, especially in women, is supposedly scarce, boys show off their actions like they've just found the Ark of the Covenant - well, yeah. In this kind of sex-as-capital culture, they have.
Another question, on a related note: How do you feel about the laws associated with underage sexting? Right now, a 16 year old girl could text a naked picture to a 16 year old boyfriend and get arrested for producing and distributing child pornography, while another 16 year old could (in some areas including my own) legally have sex with an 80 year old and have no repercussions. Should the laws be tightened on sex in real life, or loosened on texting, or neither because they're too different? Should the person who created the pictures be held responsible for creating them if they get out, or the person who distributed them, or both?