"We" are accustom to reading in a defined width/height ... eg. books, letters, etc.
People don't like reading more than x amount of words per line ... newspapers are broken up into columns for a reason
Everyone sees the same thing that you see. eg. equal amount of text; equal amount of white space, etc
TIP
You should always design with the lowest common denominator in mind.
A fixed layout is not always best. For example, a site primarily to showcase photos would be best in a variable (liquid) width layout.
If using a variable layout ... make sure the text area is a fixed width this will help ensure that your readers will stick around to read the entire text.
Nice statements
I like this post so much im going to quote it for my other thread of this.