The ability to change the Creation Date on an iPad or iPhone would definitely make my life easier. I would love to ditch the laptop and just manage my workflow from an iPad or iPhone!
I use this feature to organize my documents. This allows me to see the order in which the documents arrived, and find documents from certain time periods. I sit down every couple of weeks and scan my documents into Evernote, so all the documents scanned on that day have the same creation date regardless of statement date, invoice date, or when they were created or received. I have seen workarounds where people put the date in the Title of the note, but this seems redundant when there is already a Creation Date associated with the note.