On a problem page, there is always this box on the right which lists out the best submissions for the problem. I find it out of place here, and it reduces the width of the problem statement. Maybe the text size could be increased a little, and the problem statement spread out with the space that remains.
I don't know how everyone else feels but to me it just feels clunky and annoying. Maybe this width of the problem statement really might be optimal.
Also, if we do have something on the right, wouldn't My submissions or a Submit box be more useful? I'd rather prefer more width to the problem statements and increased text size though.