That's right - that's why Apple released stuff like GarageBand, Pages, Keynote, Numbers and iMovie for the iPad - so that people would not use all this content-creation software to create content.
Yeah I have all those app on my iPhone 4. iMove is useful if I'm out and about and want to trim and upload a video to facebook etc (these apps should really be shipped with the OS), but that's far cry from actual work or real video editing.
The other applications pages, numbers, keynote are severely limited, and really slow and difficult to use. They are OK for viewing documents created elsewhere, but not so much for creating new one.
The Isaacson biography states explicitly that Apple released those apps to counter the perception (which they disagreed with) that the iPad was for "consuming content only"...
I digress. I write in my iPad, mostly for my blog or free-form, with a bluetooth keyboard. Not perfect for TeX, but using iSSH against the cloud works quite well.
If you want to do anything that looks remotely like work you don't want to use iDevice for it.