I think Gruber's underlying point is that exclusive apps are one of the things that helps a platform maintain success, because they are a barrier to exit. You

I think Gruber's underlying point is that exclusive apps are one of the things that helps a platform maintain success, because they are a barrier to exit. You ask, "What thing do you want to do on your phone that Android can't?" This is a perfectly fair question. I think the response from the Apple camp would be that it is the wrong question. The question they're more interested in is how things are done, not what features are available. This is why they focus so much on design, polish, and experience, and less on providing the widest possible functionality. Along the same lines, notice that Gruber criticizes several Android apps for being knock-offs of iPhone apps, or for having relatively poor quality compared to their iPhone counterparts. I think this shows that his focus is on the how rather than the what, and that his discussion of exclusive apps has less to do with functionality, and more to do with how sticky the platform is. Neither side is necessarily right or wrong, but it's important to recognize that they are asking fundamentally different questions.