The app store is optimized for mass appeal apps. It only shows reviews for the latest version in your country's app store. The HttpWatch app has had a reasonable number of reviews but it is a relatively niche app.
Getting app reviews is very hard unless you have hundreds of thousands of downloads. This post suggests that only 10% of all apps have one or more reviews:
http://blog.appfigures.com/a-deep-dive-into-app-store-review...