I'll rephrase a bit. The bubble that Apple forces you into if you are a developer, is to write your code in XCode.
I'd be surprised if any approved apps in the AppStore were not written using XCode. XCode only runs on OSX. OSX only runs on Apple hardware.
The two bubbles you mention are valid, but there are more than two bubbles.
To get an app into the AppStore you must be developing using Apple hardware running OSX.
Regarding the 'Everything else is very open.' statement. If that were true, it would be easy to sync my mp3s over to my iPhone under linux. It would be easy to sync my oggs over the iTunes in the iPhone using linux. It would be easy to change cellular providers. It would be easy to play my movies purchased through iTunes under linux .. It would be easy to buy media through the iTunes store under linux .. It would be easy to save a document as an .odt in at least one Apple product .. iTunes would support OGG media without modification ..
In summary: Apple at every turn chooses the path that locks their customers into using their products.
Apple does make slick products, but they are not 'open'. I'd love to hear ways in which they are open though.