WhyYouShouldContrib

Firstly and obviously, you should contribute to QFTSOM becouse it's awesome. This (clearly) an obvious and redundant axiom.

QFTSOM is also interesting in and of itself, as shown on WhatIsQFTSOM

More practically, if you don't know python (mostly, perhaps), you will get experience and some degree of mentoring from this project. It will, hopefully, be fun.

As for playtesting, if you've always wanted to be a game designer, but never had the opportunity, this is (sort of) your chance. Most suggestions will be tried out, which is more or less the whole point.