Why bother? BitBay already has a marketplace where you can sell not only digital content, but anything. And it is fully decentralized and secure. The above idea has no solution to prevent scams like sending a doc where it only says "hello world"
if its the case, then there is many of people will only send a doc that says "hello world" like you said and i think its not good for the coin itself because many of other people will be gets scam and it will make some chaos in the blockchain. there will be thousand of transaction for sending the content digital. but all in all, i don't know and i am not sure about this, maybe its a good idea and maybe its not. its depend on what the purpose from the dev and what he wants to do with his plan.
I know scam is always a part of this game, especially when everything is anonymous. I will consider it seriously. Thanks for reminding.