Oh geez, that's an epic thread indeed! Thanks for the link.
I'm sure the underlying technical plumbing for AIR and Photoshop are related. The OSX programming model is simpler, while the Windows model is much more complex, making it much more difficult to write correct software. To me, it feels like the difference between data-binding in Flex (more limited, but super simple to code against) and data-binding in WPF (more robust, but 4 times the effort to code correctly).
Anyway, good luck with your Steam installer hack.