Hi Alex,
You spotted a known bug. The inspector does try to open the last selected presentation. If the presentation is not found, then it falls back to the first presentation (in most cases State). The problem in this case is that for a collection the title is variable (because it has the size in it - e.g., 5 Items) and because of that it is not recognized as being the same when you switch to another collection.
You also ask a relevant question: What should the default presentation be? Until now we made it State because we wanted to have as much resemblance with the classic inspector as possible. But, I think now, we can safely start to change that default. For collection, I also believe it makes sense to show Items by default.
Cheers,
Doru