Our use case:
We have various pipelines, for various sales cycles and sometimes various types of contacts or companies.
The Deal's information we need to access depend on the pipeline the deal is in. Since the "default deal properties" is made to display the "most important" information of a deal, we need this group of "most important" information to be pipeline specific.
To propose to create multiple "default deal properties", each one having a name. Then, admin should be able to decide to which pipeline to apply this "default deal properties". A "default deal properties" may be applied to one or more pipelines. It's ok to have a limit on the possible numbers of possible "default deal properties" if needed. 10 or 20 maximum would already be amazing.
Note: I've written the above with the understanding that "default deal properties" are controlling both the "about" section on the deal and the properties available when creating a new deal on the card that's opening on the right of the screen.