Definitely agree with this. There is something to be said for using liquid layouts on a site like Amazon, where you have product listings next to each other — it's useful to have more space. But it's just plain wrong to have a liquid layout on a site like Wikipedia, makes it a chore to read the thing, or just any other text-based site (brand site, blog, etc.)

I'm on a 24" iMac and my browser window is around 1200px, so I prefer not to have to cover two A4s side-to-side when reading.