I am all in favour of exclusive apps. I've been using Macs since the early 90s and I have long sought out the apps which show the most care and attention to detail by developers, conforming to all of the user interface guidelines. These apps feel so much better because they are predictable in a way that cross platform apps aren't.

Cross platform UI toolkits have their own internal "logic" that clashes with the native UI, frustrating user expectations.