That's not to say that Steve Jobs was wrong about the future, but he had to sell devices in the present which meant pretending that they were perfect even though they weren't. Ballmer may have been doing the same. It's likely that his failures occurred much earlier in the process, and then he had to try to sell doomed products which is where those silly statements come from.
They have had failures though, of course. Ping was another, for example.
Under Jobs Apple made stellar hardware and good-enough software.
Where they fail is web services. Apple cannot engineer a decent web service to save their sorry lives. The Cocoa API is pretty well thought out, generally well-documented, and pretty well-engineered.
Then you get into things where you have to talk to Apple via a network. StoreKit? [shudder]. iCloud? [terrified scream]. iMessage? Oh lord.
I agree, their APIs are generally very nice. But the last few releases of OS X haven't been great. Multi-monitor support will finally be fixed in 10.9, after having been broken in 10.7 and 10.8. Also, recent releases have become very slow. A 2009 Mac Mini running 10.8 is unbearably slow, while the same machine is on 10.6 is almost as fast as a recent machine machine with a SSD on 10.8.
And along with NextStep, Apple got its new iCEO, its new head of hardware, and its new head of software ;-)
Ultimately, you have to remember that he had an agenda, and if he wasn't selling it that day, then he would probably say something negative about the idea or implementation (of a competitor's product).
Here's a page that has more examples: http://www.wired.com/gadgetlab/2010/02/steve-jobs/
When Ballmer said nobody wants a phone with a keyboard, or that Zune would kill iPod he acted on that until reality was exhausted from beating him mercilessly over the head with proof he was wrong.
Also having to sell silly products again is the CEOs problem for having to decided to sell those. Its just that the past 10-13 years have been cluttered with bad products and I would assume the ceo had a major role to play in it.