I disagree. Once the fourth season was in full gear it had potential, problem was, it took four seasons to get to that point.
They could've easily moved into the Earth/Romulan War or the events that lead to the relations between the Federation and the Klingons during the 23rd century and all while doing so, showed how the Federation came to be. But waiting four seasons to do so is what killed the show because IMO that is the purpose of Enterprise, to show how Star Trek came to be. If they were going to just have a new crew take over the franchise why not move further into the future, out of TNG era and move forward? It's what Trek has always done, save the new movie. And even it fulfilled the purpose of a prequel, showed how things came to be, even if it was in an alternate universe.
"Death, delicious strawberry flavored death!"