Quoted from 9to5Mac with full link included:
http://9to5mac.com/2014/01/27/apple-execs-say-ios-and-os-x-wont-merge-and-10-10-will-prove-that/
“It’s obvious and easy enough to slap a touchscreen on a piece of hardware, but is that a good experience?” Federighi said. “We believe, no.”
“We don’t waste time thinking, ‘But it should be one [interface]!’ How do you make these [operating systems] merge together?’ What a waste of energy that would be,” Schiller said. But he added that the company definitely tries to smooth out bumps in the road that make it difficult for its customers to switch between a Mac and an iOS device—for example, making sure its messaging and calendaring apps have the same name on both OS X and iOS.
Of course, it appears that the Apple executives are taking shots at Microsoft, Windows 8, the Surface line of products, and
Google’s new Touch-enabled Chromebooks. Microsoft is well known to believe that computer operating systems should be the same regardless of devices. On the other hand, Apple has two complete different operating systems: one for the iPad and iPhone, and the other for the Mac. Federighi explains why:
“The reason OS X has a different interface than iOS isn’t because one came after the other or because this one’s old and this one’s new,” Federighi said. Instead, it’s because using a mouse and keyboard just isn’t the same as tapping with your finger. “This device,” Federighi said, pointing at a MacBook Air screen, “has been honed over 30 years to be optimal” for keyboards and mice. Schiller and Federighi both made clear that Apple believes that competitors who try to attach a touchscreen to a PC or a clamshell keyboard onto a tablet are barking up the wrong tree.