Saving traffic is good in general, insofar as it speeds deploys and allows higher container density.
But for me the key was trying to get out of dependency hell. The shade plugin isn't perfect.
I work at Pivotal, we inherited the Spring team from VMWare. When I first saw Spring Boot I wondered what all the fuss was about. Then I worked with a classic Spring-with-hand-rolled-Maven app and oh boy, let me tell you, I got it.
Having someone else level the dependencies for you? Huge. I'd be interest if this tool can help Spring Boot too, though the runtime downloading of dependencies is not without problems.