Well, there are some runs that would require 8 finger tapping, as well as chord-melody solo guitar that would require it, but it's definately not essential to guitar playing, like alternate picking. I mean, look at guitarists you know. Very few use 8 finger tapping and they sitll get a lot done. I would say focus on the basics first before tackling this. Oh, and if you want some coordination practice, practice some basic piano playing - especially some Bach Two Part Inventions to get hand seperation.