I think it took Apple a lot of guts to release "refactored" release of Mac OS X. I think Apple was looking at lose-lose situation with 10.6 for various reasons:
- Multiple architectures (Power PC, Intel 32-bit, X86) and APIs (Cocoa, Carbon) are taxing Mac OS X and developers with suboptimal foundation and frameworks.
- Modern CPUs and GPUs work quite differently and require much more complex programming to leap full benefits.
- Adding more visible features, such as new user interface, would justify higher price tag and more buzz, but that requires more time and/or development efforts.
- Focusing on visible features in past Mac OS X releases have resulted in lots of bugs "under the carpet" that require more substantial back-end changes. Adding more visible features often hamper these fixes.
- Meanwhile, Microsoft is set to release Windows 7 in Q3 2009.