Lieberman would have lost big as well. He would have agreed w/ Bush on most things, including the big issue of the Iraq invasion, so there is not much for Dems to get behind. Why have a fake Republican when you can have a real one? (Even though Bush is a poor excuse for a Republican).
No, Kerry was just an incredibly soft target. And still he would have beat Bush if not for Ohio. Even Biden would have beat Bush back to Texas, IMO.