I made a suggestion of my own (suggestion 7) before reading this -
http://www.scirra.com/forum/a-few-simple-requests_topic45930.html
My idea was slightly different in that the HTML files would go in folders and then at export you could pick one to use. With that sort of template setup you could then easily make a few HTML's you want to use, add them to folders and simply select whatever one you wanted at export.
This idea would only need one simple editor change also with a new dropdown list or something similar, it doesn't turn Construct 2 in to a HTML designer either because it's still down to the user to make the templates.