I suggested this as an option for those Sparkle users wanting to work with a wider page width. It would not be required to use if a user did not want to use it on their Sparkle site.
Since most desktops, laptops, and a lot of tablets and such are set to 1920x1080 now (or even wider on desktops), it would seem to make sense for Sparkle to allow for a wider device width as an option while keeping the existing device option widths. So if a Sparkle user building a site only wanted to use 1600, 960, and 320 device widths on their sites they could as an example.
Most of the sites I work on for businesses are responsive with max page widths set between 1600 and 1920 now, thus the reason for the suggestion to better fit/display content on higher resolution screen settings.
Anyway it was just a feature suggestion to offer for your consideration.