I am sorry if this is not the right place to request for a new feature. I'll be happy to post this request at the appropriate place if directed.
Widget visibility is one of my favorite Jetpack modules, and I think it'd be way more powerful with responsive conditional loading. For example, Jetpack could show/hide the widget depending on the screen width/orientation of the device in which the page is loading. The advantage of this over
display:none is that instead of simply getting hidden, the widget will not load, thereby making the webpage smaller and faster on mobile devices. With mobile devices exploding in popularity, I think many will appreciate this feature.
If there's a plugin that already does this or a tutorial on how to achieve this, please let me know.