Because I only buy cars that are an overall improvement over what I have, and the Leaf is not.
Main requirement for anything I'm going to daily drive: Must completely handle stop and go traffic without me needing to touch the pedals or tell it to resume. Leaf will stop, but not resume. There are a litany of other reasons I won't personally buy it (it's front wheel drive, it's too slow, it's a weirdo derp pod), but I hope they sell a hell of a lot of them.
Lots of places I will drive my Leaf vs my tesla.