There is one use case for such a file-system - flash cards and sticks. The 64Gb version is a tricky case. I need to use it in Android (this is sdxc card), Linux desktop, Windows desktop, hey, may be Mac too! exFAT works for Android-Windows, but not for Linux. And Cyanogenmod does not seem to play good with exFAT yet, at least the release I got.