They are similar to leather boots, only light boots weigh 5 stones less.
With their base stats, they are pretty much useless, except to protect your feet from damage while kicking a gray ooze or ochre jelly. It may be worth it to collect them still, as they are common, don't weigh much, and sometimes have positive stats, plus they can be polymorphed into something more useful. If you identify their B/U/C status beforehand, you can just try them on.