Interesting piece by Tim Morgan, definitely worth a read. In his response, John Gruber notes:

“Whether you think this is a good thing or not, there’s no use fearing it. Apple’s passion for UI uniformity went away with the six-color logo. Change is inevitable. Individuality is the new norm. Mac UI design is only just starting to take influence from iOS UI design.”

I don’t have a problem with desktop apps taking influence from iOS apps, but there are some influences that I think are bad in a desktop environment. I think iOS UI influence rooted in the fact that iOS apps are always full screen and always have your full attention are bad on the desktop.

I know Apple likes this idea since 10.7 will have API support for full screen applications. That is great for novice users (less confusing) or people who just want to focus on their task. I think good applications will have both full featured window and full featured full screen modes.

iOS applications don’t have to think about things like moving windows around. Mac OS X desktop applications still do. If you haven’t, read what Morgan says about moving windows in the new Twitter app, and how confusing it is. Better yet, try the app yourself. Where do you click to move the window? This is not even a concern in iOS. You don’t move windows. The ability to move windows in the new Twitter feels like an after thought.

Until the App Store came out, many might argue that people using a dedicated Twitter application on Mac OS X were among the technically savvy crowd, and they’ll figure it out. Post Mac App Store, this can no longer be assumed. Many novice users are going to be using these types of applications. Especially the free ones. I can imagine many users finding it incredibly frustrating to use the new Twitter application.