That's a good question, which I don't really have a perfect answer for.
Most of the chumby-authored widgets typically allowed configuration from the widget directly in addition to configuration from the website. Most of my personal widgets behave the same way. Third-party widgets, not so much, and there's little I can do about that.
Back in the early days, one of the plans was to offer the ability to provide HTML-based widget configuration as alternatives to the Flash-based configuration (the server keeps a mime type for the uploaded files to keep track of that). The central problem was that such a configuration would typically require several files (html, css, js, images, etc) as opposed to the simple single-file method used with Flash, and it wasn't totally clear how to host those files properly in a way that was manageable, secure, and safe.
I will look to see if there are any remnants of that in the old server source code - however, even if implemented, third parties would have to go back and revise their widget configuration apps to the new method. I don't know how much appetite they have for that.