There's pros and cons, android central wrote up a good summery on this feature on Kit Kat. The Pro is more security in your device as when "apps" have full range they'll store all kinds of crap here, there, everywhere. Now they can only be stored locally on internal storage, nice feature imo and why it's standard we have a 32gb internal storage device. Now if this was a run of the mill 16gb internal storage device that would be a different story
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Idea is what is stored on SD card stays on SD card and what is stored on internal storage stays there so there is no mix/matching going on and confusion. Keeps things running more smoothly and secure.
Now if you download mp3 and videos all day long on your phone and have to wait til you get to a laptop to connect via usb and manually transfer it all to SD card and delete off internal memory, yes this can be a hassle. I personally like the idea of all this overall. Only feature i wish we had was being able to transfer internal files to external sd card with a file explorer app.
No worries, once S-Off is available none of this will be a concern anymore
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