it made sense back in the days of the 'click-in' snowboards. now it's just stupid. you see tons of skiers lose their skis, zero snowboarders lose their snowboards.
here in Quebec it was mandatory on pretty much all the hills a few years ago. now-a-days they don't really check anymore. every now and then there's some guy having a bad day at the lifts that will make a big deal out of it. I just carry a spare lace in my pocket just in case.