I'll give you one reason for line length limits... being able to intercept potentially dangerous/viral code injection.
If you limit your line length to something most devs can view (120-150 chars), then the risk of someone injecting viral code into a project outside what is visible on a line is significantly reduced.
I'm not hard pressed on line lengths of 80 characters or so, I just feel that you should have a relatively reasonable limit so you can better detect the bad stuff.