When did I say you cannot be creative with an iPad? Sure you can. I don't think your work is simple, but the tools you use can be minimalist... one has nothing to do with the other. I use text editors to perform complex programming work.
My point is that word processing is still very basic and slower on the iPad compared with just about anything else. You say it does it "quite well"... but does anything not, then? A Surface 2, laptop, or desktop, are all much more efficient and capable of performing the task. So with iPad as the "quite well", what would do it poorly?
While creating a document, you might want to: use a mouse for highlighting/precision editing, be able to use an external monitor, be able to have applications (especially web browsers, PDFs, or other documents) side by side, or email/messaging apps, not have the keyboard take up 2/3 of your screen (unless you use external keyboard)...
The only situations where the iPad does it "quite well" is when the needs are quite light. The real advantages of the iPad come in its portability.