I don't think it's more deceptive than putting favorable reviews on the back of a book, or those any ads where they get actual customers to review a product. The app store is both a promotional channel and a marketplace.
On the other hand, a private engagement directly with developers could prove to be more beneficial since it allows developers know of shortcomings/user-expectations without negatively affecting the overall ratings. This way, they can improve the app without having lingering negative comments affect the perception of their updates.
Well these aren't fake reviews that appear out of thin air. The reviews may be "biased" but they're still written by real, mostly happy, users.