Scott Stevenson tells it like it is,
Even if Apple recommended cross-platform toolkits for Mac development, the basic premise of Mac software market would not change. Mac users bought the computer they did because they found the experience more appealing. Bringing an application across from Windows with minor tweaks simply won’t resonate with this sort of user.
And gives free advice,
Maybe the most important thing you will ever need to know about Mac development is this:
Mac users will generally favor an app with a better experience over the one with more features.