This is probably a dumb question, and maybe it's been answered elsewhere.... but I don't really see much benefit of the Book and Hold feature if it doesn't guarantee the PRICE!

The flight(s) I am interested in for a European trip next month show wide-open seat availability (on a 747), so it doesn't seem likely they'll sell out within 24 hours (unless they downgauge to a 777 or something, but even then, I think there'd be lots of empty seats). I thought about using Book and Hold (as a kind of experiment), but since there's no fare guarantee associated with it, I thought, "Nah, why bother."