While this could be useful at times, I think, I am confused as to what you are ultimately suggesting. Are you using <br>'s to break paragraphs? I personally use <p> to break paragraphs...

If, on the other hand, you're suggesting to use the breaks on lines within a paragraph, and I think you are, then I completely agree with davidrw that how a paragraph wraps should be left upto the person viewing it. I have a large-ish screen, I thank you for allowing me to use the available space and set the width that I like, and not force your paragraphs to wrap sooner; unless you have good reason to do so.

-Scott

Update: fixed some grammer issues...