Examining MicroSD changes in Android 4.4
 

While Samsung Galaxy devices had new restrictions on microSD read/write access, it was hard to say whether this was the start of a trend for all Android OEMs as restrictions on microSD were bypassed by most OEMs, as the vast majority of functionality such as moving apps to microSD were ported to Android 4.x builds. The story is more than just about Android 4.4 though, as the change in microSD functionality happened some time in the 3.x releases of Honeycomb.

http://www.anandtech.com/show/7859/e...-in-android-44