The reason I have not used my iPad for serious work (As in, developing software, writing my documents, checking e-mails) has nothing at all to do with the storage available on it.
With my PC (Or even a Mac) I can do all the stuff I want to do on a Mac (given that I can replace the OS on the Mac with linux, as Mac OS is a bit too much of a (my personal opinion remember) toy for serious work other than writing, photoshop or any other artsy productivity). And I can do it all on my PC as well.
The reason the iPad pretty much solely as a reading device these days is simple. Its form factor and user interface suck (again, only my opinion). It is when I can install any software I want on it without being held back by the app store. The day it becomes professional is when I can load any music, files or documents onto it without the need of secondary software (iTunes). It is when I can actually do work on the iPad without feeling constrained by the display and size of the device.
It is when the device and its operating system stop feeling like a "gosh apple is cool" kind of advertisement/toy/gimmick.
That blog post read like the rant of a overzealous apple fan fawning over the newest apple product. What about extra space changes it towards being a professional-grade machine today when we have almost unlimited cloud storage at our disposal?
I've read a few comments that say the same but I've never understood why. What serious work do you do that OS X isn't good enough for or what does it not do well?