The ease at which you can 'fool' machine learning right now adds an additional layer to practical machine learning in the wild - risks from malicious attacks.

Imagine someone putting up a lawn sign that tricks self driving cars into seeing something that isn't there and applying the wrong behavioral pattern because of it. Or even simpler, someone taping a sticker over the self driving car's cameras that cause erratic behavior. Can have really bad consequences and seems really simple to do.