Good idea, especially if there are lines of text on the page. It can be difficult to read long lines of text. Even better to break the width into columns of content that can nest the least critical parts of content under the main content at narrower widths.
An example is this page - you can stretch it across an extra wide monitor, but it gets hard to read. The sidebar gets wider, but the lines are still too long for comfortable reading. I may be wrong but I would think it is rare that anyone would want to see pages wider than 1600 px - unless for videos.