Because its interesting. Well i find it interesting that i can be moved without being touched.
In a "real fight" your going to do what your trained to do aren't you? Be it Grapple, Strike, Grab nuts if want, ok.
Thats what you train, be it forms, katas, sparring, MMA, Thats what your going to have when fighting.
Everyone knows your attacker isn't going to be compliant, and if you don't you will find out pretty smartly
I don't know much about Dillman either, but he was a karate national champion four times.
http://www.dillman.com/about.asp