There's actually a couple other reasons, in addition to the unstated reason of avoiding the FAT patent. First, if you put in a cheap (yet large capacity) SD ca

There's actually a couple other reasons, in addition to the unstated reason of avoiding the FAT patent. First, if you put in a cheap (yet large capacity) SD card in a device, then it will take an extremely long time to index the files on it (such as getting the id3 tags out of the mp3 files). That in turn makes the phone appear to be a low-quality device for a lot of users. Now add onto that the current trend that the user doesn't need to know where files are stored (they aren't stored on devices or file folders, they are associated with specific applications), then you have a usability problem.