Eh, I don’t think it’s the same thing. The gulf between “photos user” and “pixelmator” user is quite high, much more so than “weather app” and “weather app but better”.
In particular, if you have the average user Pixelmator, they’d be worse off. The same isn’t really true with weather or darksky - they really just do the same thing.
We still have iMovie and FinalCut, GarageBand and Logic. Apple has kept two different product lines before.