I think something similar to creating a webpage on WordPress would be cool, you can drag and drop all the UI elements you want, change their icons and stuff, and then you click submit and it compiles a client for you would be very cool. I'm skeptical of building those features into existing clients would work well, it seems like any program that does that lags like a mofo.

As a separate matter I think having a similar tool to create something like a storefront would be awesome. I can imagine a store where the seller could live stream themselves building the products in the center with a few products arranged along the sides, and then you can live chat the seller asking information about the products.