Intel's diversification probably has more to do with internalization of the mantra "if you're not growing, you're dying" than pressure from Wall Street.
Apple's smart growth is much better than the flailing growth that many companies attempt. E.g. Google has search so Microsoft does Bing. Apple has the iPod so Microsoft does the Zune.
New products are OK if they are clearly better than what is already out there, but in Microsoft's case they weren't. Contrast with the iPhone. It was IMO clearly better than what was already out there, if for no other reason than Apple refused to be the wireless carriers' bitch.
But now even Apple is doing share buybacks, because they're running out of smart diversification ideas. An iWatch wouldn't be big enough to provide meaningful growth. I'm sure they'll eventually do it, but the law of large numbers is no longer on Apple's side.
The example I gave of me wanting Intel to become a world class foundry is IMO smart diversification. TSM's market cap is about $93 billion. So, clearly, there's room for competition.