I completely disagree. Not because I'm a graphics whore, but because this is Uncharted. The way people in this thread are talking about how important co-op is you would think none of them have even played Uncharted. The game is meant to be a single player experience. As far as I know only certain parts/missions of Uncharted 2 are meant to be played in co-op, the rest is still just Nate. I will admit, I'm dissapointed that there will be no split-screen co-op, but if puting it would have meant visuals that were inferior to the first Uncharted then I completely understand where they are coming from.
It would only look worse than Uncharted during splitscreen play. Putting splitscreen in isn't suddenly going to make single player look worse.
So, if it's like WipEout HD, and they just reduce the framerate and visual quality during splitscreen play, so be it. At least then there is splitscreen play. WipEout HD didn't lend itself to it very well, since it's a game about travelling at speeds of 500 km/h along a narrow track (with great graphics and effects), but it was still functional, and while it wasn't as polished as single player, it worked.
I'm not saying the single player campaign should have co-op of any kind, that's ridiculous. It's Nate's adventure, he's usually alone. But with the co-op campaign which has three people playing anyway, why can't two of them (three is a bit much) be on the same system?