The idea that the expansions available on iPad is even remotely comparable to a full fledged Windows portable machine like the surface is insane. I've tried them all on Apple devices, from things like the HyperDrive to the Mophie devices for the iPhone. All are a kludge and are inelegant at best.
I totally agree. I can't even see the point of iOS anything until they add proper file support.
One thing also to keep in mind is that Windows 8.1 actually lets you use the SD card as a drive for any purpose. Install programs, etc...
Android likes to limit your applications to the primary storage and you need hacks to relocate them the SD. That is my experience anyway.
I put Photoshop 7.0 on my dell venue 8 pro. not real usable without a mouse but it sure does fly....