The numbers don't tell the full story.
The development of Mac OS X was the development of iOS, and it was one-way.
The development of Mac OS X was the development of iOS, and it was one-way.
Apple, like you, can only think in terms of revenue and profit generated. "iPhone makes this much profit = iphone gets this much development".
That thinking has led us into this stagnated crap, because it's a terrible way to do software. Worse, what's happening now is apple is taking its iThing software and trying to migrate it to the mac. The Mac is now getting destroyed by the iPhone development.
That is the reason why.
Wow.
The smart move is further development of the Mac to explore ways to bring new features to the iPhone or future apple devices. To simply go "this = profit = all development goes there" personifies a lack of wisdom.