You definitely can use it for leg space, or rather, for knee space.
You're not going to stretch your legs into the isle, but just poking out your knee a bit can give much desired relief for those with long legs.
For me on a budget airline, this tends to be worth it. Even more so if the person in front of me decides to recline their seat.
For me on a budget airline, this tends to be worth it. Even more so if the person in front of me decides to recline their seat.