Better Interface for Document Setup / Artboard properties
When working with only one Artboard (in my case: 99% of my projects), it feels very uncomfortable to change the size via Document Setup - this shows a button 'Edit Artboards'. Clicking that button doesn't give any feedback to the user. We still have to find and click 'Properties'. Three clicks for such a fundamentals task. My requests:
1. Please integrate the Artboard size of a single Artboard document directly in the Document Setup panel.
2. When clicking 'Edit Artboards', open or bring to front the Properties panel.
3. Add a list or dropdown of existing Artboards in the Document Setup panel

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Yes, before CS4 Document Setup had Width and Height there.
But switching to Artboard Tool with Shift+O (which is even shorter than Cmd+Opt+P) should display the artboard size in either Control or Properties panels. Add Enter after this — and you get the Artboard Options dialog, with Width and Height right there. Very similar to how it looked back then.
This is fast, easy to get used to (I had the same problem as you) and doesn’t need a new modal behavior you propose.