I mostly just think they look cool :)

In the post there's a demo on how to use the same algorithm that generates Voronoi diagrams to render 2D drop shadows with a spread radius.

You may also be interested in Alan Zucconi's article on Voronoi diagrams where he outlines a few use-cases in games: http://www.alanzucconi.com/2015/02/24/to-voronoi-and-beyond/...