There's been a lot of consternation over Apple's closed policies especially with regard to the iPhone. At the surface, these feelings may seem valid. But for those used to the Apple experience for long - and I am not referring to techies here - these policies go a long way in making life easy.
I do not believe that Apple does most of what they do because they are evil, control freaks. You have to understand that a large percentage of people who use Macs are non-technical people. They are not from a software background. So, while it may seem ridiculous for a programmer to not be able to explore the file system on his iPhone, the average Joe or Ram does not even know (or care) what a file system means.
When people buy a product from Apple, they expect a seamless user experience. They want to be able to get things done. They do not have the time or the inclination, for example, to use a piece of software other than iTunes to sync their music. They typically want something that just works. They couldn't care less about the open source movement.
If Apple started supporting other music software, for example, they would get unnecessarily bogged down by the gazillion different pieces of crap available in the market. Why bother, when iTunes works for most people?
Even the app verification process at Apple, which has flummoxed many, is really more likely a process that isn't working than a display of Apple's paranoia. The clause that apps should not resemble functionality that Apple provides by default is well-meaning in my opinion. Most users don't like options and they don't even know this. Apple does and you can't argue with them when they have been providing unmatched usability in all their products for so many years.