First of all, this is something that's always bugged me when using twitter, and I like seeing someone address it, but I have a comment. I agree with the 13" laptop screen examples, but how many people browse the web full screen on monitors over, say, 21"? On my 24" monitors (1920x1200) I usually have browser windows dragged to 2/3rds of the screen at most. Most websites look patently ridiculous at full 1920 width, let alone 27" or 30" monitor resolutions like 2560x1600.