Sometimes we wonder why certain features that are released in a new major version of Android are not adopted by manufacturers. They do not have the obligation to do so, but if Google includes them, it will be for something and for a greater benefit for the user, as happens with a feature that will surely interest you, since it has to do, and a lot, with the use that we give it. to a microSD card from an Android device.
In Android 6.0 Marshmallow the option "Adoptable Storage" was included. This feature format and merge storage of the micro SD card into a single memory partition, allowing the OS to directly install apps and media on the card as if it were part of normal memory. After some testing at MWC, it seems that the new LG G5 and Samsung Galaxy S7 they do not support this feature.
The reason that Samsung has argued: «We decided not to use Marshmallow's "Adotable Storage". We believe that our users want a microSD card to transfer the files between their phone and other devices (tablets, laptops, etc.), especially the photos and videos that they shoot with the camera. With "Adoptable Storage", the card would be erased the first time it was inserted into the device. This behaviour would shock many users and we don't want them to lose their files. Second, once Marshmallow starts to use a card for adoptable storage, it cannot be read by other devices, so it loses the ability to be used to transfer files.«.
Samsung's argument is valid, although Marshmallow's default implementation allows users to treat the microSD card both in "portable" mode, allowing it to operate as a normal one, such as in "internal storage" mode, in which a user could maximize the total size of the internal storage.
One of those characteristics that for users who have a penchant for microSD cards large size, they would like to have on their phones.