The stats don't make any sense and there's been a constant complaint in the forums about the difference between impressions and installations (don't forget if a user signs into multiple chrome devices/browsers those all count as separate installations).
In short, I agree with everything you've said. It's not enough just to have a place to list your app, having good store tools and user communication tools goes a long way to delivering a good product.
We added a B2B app on there a few years ago. Generated lots of traffic, most of it crap. About a year or so ago the traffic started to die off.
My guess (although this is completely unsubstantiated) is that Google realised their Chrome Web Store was another free channel app developers could use to promote their products. There's little upside for Google, and they would much rather the developers use paid (Adwords!) channels instead. Just a theory...I could be way off the mark.
