DS9 already showed us ship battles and surface battles. They showed us the personal and psychological cost of war. And unlike "Enterprise" would've been, DS9 wasn't hamstrung by the premise that the main characters can never SEE what the enemy looks like. (They made it work in Romulan arc, but three episodes is a bit different than, say a whole season or more).
In a way, you could argue that they'd already covered a war storyline in season 3.
So how could "Enterprise" have made this work?