This feature request really comes in two parts:
The File menu should have an option for opening recent files. Bonus points for also adding an option to open recent directories / repos.
OS X has a pretty slick UI for opening recent files if you’re using a trackpad. Swipe down with three fingers and you get something that looks like this:
(Screenshot from Chocolat)
I’m not sure how complicated this would be to implement, but it’d certainly make Atom feel more at home on OS X.