The whole set of reasons I softfork most android UX 3rd party libraries is for these reasons:
1. Google never, and I mean never, deploys enough Engineers to have a fully Android Support Library solution to the many UX and feature changes it makes per major Android OS version. We usually end up with an average effort after 8 months or so after the Android OS version release. This harms the goal of making an android app behave and look the same across android OS versions which is somewhat important to user happiness and on boarding efforts.
And due to more than two versions of Android OS being in the device market at once this a unique problem due to the android platform fragmentation as iOS app developers do not face this problem.
2. The Average Android Developer may get back-porting concepts right as far as the way to back-port a certain feature but usually lacks full knowledge of the Android Support Library internals to pull it off correctly.
3. Having cleaned up and curated those libraries allows me to maintain an encyclopedic knowledge of the Android Support Library internals and provides me with an edge in guaranteeing specific look and feel across android 4.x to android 7.x.
I just have to figure out what visual formats to use in showing off the demos. Should it be just UI controls or more expansive UX demos or both sets of demos.