It's just the style now days. It's funny when I was in high school in the 80's we wore our jeans so tight the girls used to use a pliers to zip them up, I had a pair like that and they were not comfortable at all! Now I wear them to fit, not too tight or slightly baggy I draw the line at underwear showing. My friends daughter is 16 and she does the baggy everything hip hop look, it's even worse when girls do it cause some times you can see their thong, not boxers, thong. So be glad they are boys
It's fashion give it a while and it will change, other then formal night should not be a problem at all some day they will look back and say I can't belive I walked around like that, it's part of growing up and trying to fit in, with others their own age.