Monopolies are expensive. If there was just one console, that one console could cost however much they wanted it to (they being the people who owned the copyright). Currently, the 360 is extremely affordable and the PS3 is only for those who can afford it. If there was a single console, they could make the price as high as $600 and still profit because there would be no alternatives. Everyone would save up their money to get it. Right now, if someone can't afford a PS3, they get a 360 first (unless they're a microsoft fanboy, in which case they'll never buy a PS3 even when they have the money). On the bright side, developers would only have to make one game, not 2 or 3 (360, ps3, and pc) which means they could devote more time and resources to making that game as good as can be. Also, people wouldn't have to worry about some awesome game coming out exclusively on the one console that they don't have. I prefer multiple consoles, one cheap and one expensive. That way everyone can play games.
NOTE: I know I never mentioned the Wii. That's partly because I hate that damn thing and partly because I was just referring to hardcore gamers. I've never seen a hardcore gamer choose the Wii over the 360, especially since they're the same price (the arcade version is actually $50 cheaper than the Wii).
