User blog comment:Susanolivia/Fixed Width, Sidebar, and the Removal of Monaco/@comment-3139726-20101020173231/@comment-1025281-20101022101738

The screen width Wikia has chosen accommodates laptop users and netbook users, which are a significant share of PC users today. These netbook users and users of smaller, higher-end laptops rarely have a screen wide enough to fit the kind of situation you describe. In any case, if you are very concerned about wastage of your screen space, then you can always add stuff to your user CSS to make the page fit the screen.