Clearly you haven't used these "productivity" apps. If you had you'd realize they are highly watered down versions of their real counterparts. Even if you had a filesystem and printing, you'd quickly find the apps to limited for any real work. They are intended for quick / minor edits and reading. That's it.
I disagree with that based on the demos and sample videos they've given of these apps. Some of the stuff they do is pretty advanced. Take for example data entry of soccer statistics they showed, pie charts, newsletter production. That's not tweaking, that's creating. Productivity.
And even if you do accept the "just lightweight for quick editing" argument, that doesn't change the fact that it's a major PITA to get files back and forth between the iPad and the desktop or cloud, which, presumably in your model, is where you created the documents. It's unacceptable. If it works for you, I'm glad for you, but I think Apple is going to face a huge backlash on this issue and they will have to relent at some point. As others have said, even just a simple single syncable (hopefully wirelessly) dropbox would be a huge improvement and suffice until they want to refine it.
Here it is in Apple's own words:
iWork productivity applications make it easy to create beautifully formatted documents, stunning presentations with animations and transitions, and spreadsheets with charts, functions, and formulas on your iPad. Based on the iWork suite for Mac but completely redesigned for iPad, these apps — Keynote, Pages, and Numbers — are the first desktop-class productivity suite designed specifically for Multi-Touch. They’re both easy to use and extremely powerful.