I very strongly disagree with the dark sky example. Apple forced developers to completely reintegrate with the new API and released a vastly inferior weather app for consumers. Soooo many third party weather apps were killed.
I think Dark Sky firmly belongs in the "Aquihire" category. While I can't say Apple "did me dirty", I think they did themselves dirty by buying a great weather app, scuttling it, and then not doing a good job (any job?) of integrating what made the original app great. I don't feel like I - as a user - got anything out of that deal, and, frankly, I don't understand what Apple got out of that deal.