Norm these are good questions.
If the "http://localhost" trick works, it means that third-party website developers can make web games and apps that support my user-interface device when somebody visits their website, seamlessly.
Also, it means that I can include a web server as part of the hardware installation (with the user's knowledge) so they can use the hardware device seamlessly with websites that want to support it.
If it does work, I hope it works forever too. There's surely a balance between security and user-convenience!