TBF, I don't think the author is saying that Github needs to be fun, but rather that it used to be and now isn't. It's lost a nice quality that it had.
by the way, the trending page is not everything about github!
i keep discovering and bookmarking github projects every now and then. for example, this repository where the author has implementations for trigonometry functions in k&r c: https://github.com/richgel999/triglib
i don't believe github has lost its quality either!
they recently pushed that new layout preview that made the app usable when my zoom level is at 150%. i was very happy about that. i can't wait for github to provide a better search engine. and i have the feeling that they are totally working on it :)
I agree that a lot of the recent changes to GH have been really cool. This article sort of makes me wish that features like the trending page were more configurable.
Any karma system (in this case GitHub stars) can be gamed, exploited, and used to generate hype.
I would be very glad if GitHub started moving away from that (although I have no clue what would replace it, if anything at all).