Adding a CO-Op focus to the game would be smart. And if done properly, it would allow for you to basically make the old game, play through the game almost exactly like the original with a few added elements into the game. Or take a brand new original path through the level as the partner...and the levels can cross so you work together. Think of it like Time Crisis, the same level but fews different, because you have different objectives.
Actually, I don't think the game looks that bad. Is it inspiring graphics? NO. But by no means is it sub-standard.