I think one cause may be that the videogame press covers only one segment of the market. They're inevitably aimed at hardcore gamers, a pretty small segment overall. Groups like the new gamers the Wii brought in won't find much use in the press because the games aimed at them tend to either get ignored completely or reviewed in the wrong way. Who cares that, say, My Aquarium doesn't have any gameplay goals? It replaces those DVDs that show a video of an aquarium, it's not trying to be Feeding Frenzy. When the things the reviewers value are different than the things the readers value (be it art style, online multiplayer or even moneyhats) the value of the review drops and the readers stop reading.