There's another brilliant app rating pattern (perhaps a dark one). A dialog pops up and asks if I loved their app. A "yes" takes me to the marketplace for rating, but a "no" only allows me to send them feedback. It both positively skews the ratings and collects feedback from disgruntled users.
Not necessarily dark though... as an app developer I'd actually really want to hear the feedback from the people who dislike my app. As in any business, oftentimes the most disgruntled customer is the one that can provide the most useful feedback.
An even smarter way (in my opinion) of getting 5 star reviews is by showing the dialog only after x hours of use. Users most likely to rate badly will have the app uninstalled before the dialog shows.
Which benefits everyone if the problem is a simple thing you can resolve by helping them directly. Support is also part of the experience, and good customer support should factor into the review as well.
I can see how you'd see this as providing a positive bias, but I see it more like getting a chance to see if you can't help the customer out before they give up on your app. It also reminds the customer that there are people on the other end - so even if the issue can't be resolved, and you still get a one-star rating, the level of vitriol seems likely to be reduced - something all too easy to forget when angry-reviewing.
Of course if they just take the feedback and dump it, that's a different story - but again, I would think anyone with that experience would still leave the negative review.
TL;DR - too many downloaders use negative reviews as a combination support request and cudgel. I think this is a reasonable defense against that.
Users with negative experience are more inclined to leave a rating than users with a positive experience, which makes the ratings not reflecting the reality of the overall user experience in the first place. (http://cdn2.hubspot.net/hubfs/232559/The_Mobile_Marketers_Gu...)
This technique is a genuine way to encourage sharing positive experiences about the app. In the same time, it offers a chance to the app provider to improve a bad user experience.
Whether it's a dark pattern or not, I think really depends on the motives, are you genuinely trying to make the app better or are you only interested in the people's perception of it.
And you almost need to this because app store reviews are so deadly otherwise. You have no way to respond to reviewers (who've had problems) as you might on TripAdvisor and virtually no one goes out of their way to find an option to send feedback before going nuclear in a review.
