Typekit and Instagram sold. Sparrow, like so many before them, sold out. The discontinuation of further development on the product may not be as disrespectful to its customers as the full killing of it, but it’s close enough for widespread discontent among those (paying) customers to be fully justified. Maybe Sparrow’s creators will get to make Gmail a significantly better email client for the world; but maybe the priorities of a giant corporation are not so much concerned with that. I think a lot of the discontent stems from the fact that many of these customers weren’t using Gmail (as an app) in the first place.