In my opinion the non-functional requirements that Sun pursues in their Pet Store application are certainly valuable in themselves. However, they bring about practical issues. Sun should have addressed these as well. It is possible to make a clean multi-platform design and then optimize it for performance. You probably end with a design that is reasonably clean as well as fast; and everybody would be happy.
But that's not Sun's way; and it strikingly illustrates the difference between Sun and Microsoft. Of course, they both want to dominate the IT industry. If Microsoft is more succesful at it, that is not because their initial designs are better; far from that. Usually, their first versions are really not good at all. Maybe they have also lied and cheated their way to dominance. What strikes me, however, is that Microsoft will always come around to addressing the practicalities that prevent their designs to be succesful at first. They will just keep on trying.
Sun, on their side of things, are stubbornly deaf for user complaints. We've known for years, for example, that Swing is too slow for desktop applications; even though Swing is a brilliant design. There's a big market out there for desktop applications and a lot of development starts there. How many millions of times have people raised this issue? Well, not even with a forklift has anyone been able to move Sun to do something about it.
Another practicality would be the fact that .class and .jar files fail to blend in seemlessly in an environment of .exe en .dll files (Windows) or in an environment where .so files are customary (Linux). How many millions of times will we have to raise this issue?
Sun's stubborn refusal to do something about these practicalities has allowed Microsoft to remain entrenched on the desktop, keep it all to themselves and continue to prosper there. Well, from their trenches on the desktop they are now launching an impressive counter-attack that could very well spell the end of Sun's server business. They can only blame themselves for that.