Allow values to be passed to the Excel sheet from the form URL.
I'd like to add a value to the form link. For example, when I send a form to different groups I can add an identifier for the group in the link rather than make respondents tell me how I sent them the link.
This is really important for serialising data collection, as for panel data, or for getting back to someone after an initial response from someone else. It allows chaining of the data and takes data collection to a different level. It is also very easy for Microsoft to implement, if only they invested a little more in the continual development of these products.