Of course casuals are the lifeblood. We the, hardcore, narcissisticaly assume that we are the lifeblood when in reality we are actually an extreme minority. A very vocal minority, but a minority.
I prefer the term "Mainstream" gamer. "casual" seems to imply these days that they only play wiisports and marioparty. If that demographic really exists, I dunno. But the mainstream gamer is the one you described. They buy a handful of games over the course of a system's life, but they number in the tens of millions, and thusly are an economic power to be reckoned with. It's these mainstream gamers that decide the victor. And they don't flock to whichever system has the highest tech, or whichever system has the most exclusives, or whichever system has the most high ranking games on metacritic. They (A) go where they perceive success. Or (B) they go where there is one game that they think looks cool.
They (the casuals or mainstream gamers) are the driving force behind the industry. We are just very noisy commentators.
You can find me on facebook as Markus Van Rijn, if you friend me just mention you're from VGchartz and who you are here.
