I think a lot of designers don't realize how important copy is in their design.  When you design for the Web, content is king, and presentation is secondary.  So generic "Lorem Ipsum" filler text is great (a heck of a lot better than text text text text text text text, you get the idea) for paragraph copy, but it shouldn't be used for navigation or page headings when mocking up a design.  The way a design looks says a lot about its content, and vice versa.

A page heading that reads "Links for Nerds!" has a lot more impact than one that reads "Lorem."  These headings, links, banners, etc give a clear indication to what the page is about, and therefore how to interpret the text.  Your design will be much more meaningful if you design around the content of the site.  There is a reason that template sites look-- like template sites.  If your text says "Simple Recipies for Cooks a Budget" but your imagery says "Motocross Racing Meets Computer Superstore" then you probably need to reevaluate your design.

That's my 2 cents.