You can add a keyboard shortcut to open the plugins panel with CMD + SHIFT + P or you can assign a keyboard shortcut to your panel in the manifest to open your specific panel. When you do this it does restore the last closed width.
However, @kerrishotts mentioned the team was contemplating adding a rich text editor in XD (or support of it). To me, I find it hard to write something in such a small column.
So if there’s ever an option to enter rich text or a situation where you might be doing some typing I’d want to make sure that the panel is set to a minimum width, at first, to display the full size of the plugin. They could shorten it if they like.
But there is another case where if there ever is a RTE then I might want to open the RTE to the same width as the scene node so the user typing will get the same line breaks and have an accurate estimation of what the text will display as. If you have text field of 50 columns then having the panel match the width give you that higher fidelity. If you select another text field that’s 180 columns the the panel can resize to that. It could be an option to match the width of the selected element.