I wouldn't call Wii Play a AAA title, but I would call it a no-brainer purchase for $10.
I'll respond to the original post with my own experience. For me, Gran Turismo 3 was a system seller. I bought a PS2 and only GT3 with it. That was all I needed.
...except, it really wasn't. GT3 was the one game that pushed me over the edge to buy the system, but I knew the PS2 had a massive library of games, and that I would later buy more games for it and get my money's worth on the system. And indeed, I ended up buying 3 more games for it over the next year, as well as borrowing plenty of games from friends of mine who owned PS2s. I borrowed a lot of PS1 games, too.
Here's the major difference between my example and, say, the PS3: When I bought my PS2, it was $180. At that price, it took a massive library of games plus one game I was completely nuts over to get me to buy it. If you want me to spend $500 on a PS3, it's going to take ten games that I'm completely nuts over. And I'm sorry, but I don't go completely nuts over that many games. On average, there is maybe one game per year that fits that description.
The other thing to consider is, when GT3 came out, it was unlike anything I had ever played before. GT4 and GT5 are evolutionary changes, not revolutionary. Sure, there are good reasons to buy GT5, and if I already had a PS3, I wouldn't hesitate to pick up a copy. But is GT5 reason enough for me to spend $500+ when I already have GT4? The biggest selling point for me is online racing (which was supposed to be in GT4, but nevermind that now), but I want to race against my friends, not strangers, and none of my friends have PS3s or plan to buy PS3s. All of them have PS2s. Think about that...












