If you want more proof that it is not a passing fad, the following game titles were developed with Cocos2d-x and JS:
Avengers Alliance by Marvel Entertainment
Star Wars: Tiny Death Star by LucasArts
Family Guy: The Quest for Stuff by TinyCo, Inc
Diamond Dash by Wooga
BADLANDS by Frogmind
Just because it has the letters JS on the end, everyone assumes it is some mashup, or as you say "cherry-picked features bolted on". Why don't you actual install and look at Cocos2d-JS before making an assumption. I purchased Construct 2, but have not used it since I have moved to Cocos2d-JS as you refuse to support it as an export option.