The dashboard is the favorite and most used report by far. It's default report for most users, but also is the most exciting way to start Piwik since it's fully customizable.
Users load their Piwik on phones, tablets, TVs, consoles, and video projector (real example from Greg who suggested this ticket!). When loading dashboard on these with 1024 resolution or less, the widgets are too small and not usable. This leads user havingg to change the layout, or create layouts specifically for mobile.
Ideally the dashboard would work without requiring user config:
So with this feature it would make it impossible to display more than 2 columns when resolution < N. I think it's an acceptable loss of functionality for the gain in user experience?
Looking good, to me.
Just one addition: in the future this could be extended to adapting to one column for even smaller screen sizes (< 799px). Together with a responsive top navigation (select-input instead of tabs) this could make the Piwik dashboard way better usable for mobile phones too.
Btw, I'd disable the moving of widgets on mobile devices, as this might interfere with the ability to scroll on touch screens. I think it's ok if the widgets are just there in the same left-to-right order the user has dragged them on Desktop device. Mobile devices can be considered as secondary devices, and it's ok the limit the features.
+1 for disabling widgets dragging feature in this special mode. This would avoid losing the custom layout.
I don't think this is needed anymore with the latest Piwik 2.0 css improvements.