@xrevan86 In short, the decision to switch to # 7.0 minimum was made to motivate me, @yvolk - developer of #, to continue active improvement of this # application.
I am a professional Java/Scala developer, and as a majority in our profession I need to keep my skills up-to-date. Starting from Android 7, developers can use all new and trending features of Java 8 and modern application approaches, including functional programming. Especially after mastering # I simply cannot use outdated language patterns... As one of my colleagues put it: I simply cannot afford writing for free something that is not a "Cutting edge".
I think that this is not bad for all of us in the long run?!