Currently it is not possible to have dynamic defaults for parameters because

The existing frontend logic only uses default_value for the parameters on initial page load. For any additional responses from the websocket, the value is used instead of default_value

Goal:

The frontend should only send parameter values for parameters the user has modified since the last page load.

This means that the last modified parameter value and all previously touched parameters values will be sent in a request.

Since value and default_value are always the same the frontend will use value if it exists and is valid. Otherwise, in case of input, textarea, dropdown and combobox components, the initial form control value will be considered empty string "".