The Internet is hard at work debating the merits of the Nexus 7 tablet, and the biggest arguments are about the lack of expandable storage, or an SD card, as you likely know it. It seems like everyone and their brother has a theory about why the hottest tablet to hit Android so far will be shipping without one. The most popular reason revolves around some conspiracy that Google is to forcing you to use its cloud services. While I'm sure Google would love nothing more than users depending on Google Drive or Google Music -- and there's certainly a big push for it -- that's not the reason devices have been trending away from expandable storage.
Wanna know what it really is? Sure you do.
The lack of an SD card in Nexus devices is nothing new, and we've been over this issue already when the Galaxy Nexus first appeared.
We got tired of seeing OEMs include many GB of internal storage for music, while users were still running out of space for apps and data. This approach lets us merge everything on one volume, which is way better.
-- Dan Morrill, Android engineer at Google
Google still supports removable storage in Android, but it is leading by example and providing phones (and now a tablet) with one big block of storage that users can use for anything they like -- be it media, documents, or apps. There are a couple of side benefits to this approach as well. The first one is a bit geeky -- it allows the device to use ext file systems instead of a mix of ext and FAT. This is faster and safer -- both for the data on the device and the way it's handled, and access to our own personal data. A journalized file system means fewer file errors, and ext preserves file system permissions so random code can't find your pictures or documents folder.
Another benefit is that the host machine (when your device is connected to a computer) can't muck things up and molest the file system, as it doesn't have block-level access to the files. Instead, a proxy FUSE (Filesystem in Userspace) file system is used to mount a psuedo-SD card folder so that your computer can read and write to it via MTP. This means you won't get errors from incorrectly unmounting your phone, and the device still has access to all the data even while plugged into a PC.
Does Google want you to use Google Play and its cloud services? Of course it does. But there is no secret evil cabal in Mountain View that held back the SD card slot to force it on you. In fact, you're still free to use other cloud solutions like Amazon, Dropbox, or even a shared drive on your desktop PC. Nobody has to like the fact that Nexus devices ship with no SD card slot, but let's stop looking for conspiracies when we already know the answer.