The primary issue here is I think that it's hidden even when there should be things to restore.
Related: Hiding it when there's nothing to restore (if that's what's happening) is confusing (in my opinion), since someone who's looking for it in it's 'normal' place will have no idea why it's not there. Also, another developer lost all their tabs when updating today, and was confused by it not being available (even if disabled). He was lucky that someone told him he could use meta-shift-n (reopen most recently closed window) and he got them back.
I use this (in some of my test profiles) at least once a day. I suspect that some users who don't want to always restore tabs/windows use it whenever they do want to continue from the last session; when they accidentally close the browser, etc.