I have two questions/suggestions:
1. Have you considered making the "embed"-widget addible in other widgets? (for example the "list" widget?
2. Have you considered making the "embed" widget connectable to data (like the "text" widget is) ?
An example use case for this could be embedding a progress bar( or other infographic not currently available) for each item in a list through the html block in the "embed" widget, where the html itself gets the progress information from an expression based on fields from the specific feature in the list.