It would be awesome if you could choose what the field types were for the flows and what fields are required. Currently, you can only populate the given areas with what is sourced as dynamic content to the existing fields. If you could control what the actual fields were as well that would be awesome.
For example, if you are building a flow for updating a contact in MailChimp, if you could map the MailChimp contact fields to the Flow builder card, then use the dynamic data to populate those fields, you could create a Flow that would update individual fields in the MailChimp contact. I know there are potentially ways to work with this in Azure or Dynamics, but those are beyond my skillset!