It seems odd to me to knock off points for not having something; shouldn't games be rated, within the category of gameplay (if you will), on how fun, long-lasting, and/or (enjoyably) innovative they are? If such a game had those qualities to the extreme, would it not get a perfect score (in that category, of course)?
I mean, one could always add more to any game, and, hypothetically, make it more enjoyable, whether it be in modes, levels, number of players, never-ending download content, etc. So, to score a game on lacking those things would always result in a score of 0. A game should be rated, then, on how enjoyable it is; if most people would play it for thousands of hours, then that would be a 10.
Unless, of course, IGN was only saying that the game wasn't altogether as long-lasting level 10-scoring game, and were only suggesting online as a remedy to that.
Okami
To lavish praise upon this title, the assumption of a common plateau between player and game must be made. I won't open my unworthy mouth.