Price certainly can be the deciding factor, especially in a purchase like a game console.
The thing is, unlike phones, people who buy from a new generation of consoles don't know that the next one will do what they expect or want it to. If Apple, say, screws up their antenna so that holding the iPhone "the wrong way" causes it to lose a big hunk of signal, that's unfortunate. But when all is said and done, their customers still have a nifty li'l phone and a whole bunch of apps and GPS and a camera and so on, and most likely with a faster processor and other neat tricks from what the engineers at Apple learned from the last version and hoped to improve on for the next. The bottom line is, it still does at a minimum what people have come to expect from an iPhone.
Conversely, about all the buyers of a new console know is that it will play games. They might know that it connects to the Internet; they might know that it plays Blu-Ray movies. What they don't know is if there will be games on the system worth playing. If the Internet service will work properly, or be easy to use, or have support and a community to make it worth using and worth suffering through any early labor pains. They don't know if a new media format like Blu-Ray will receive the support it needs and become an industry-dominating medium, or if it will fritter out and become the newest BetaMax. No matter how informed a customer might be, they can't predict the future, and the possibility of spending the highest price among the available options to buy what turns out to be an also-ran is a genuine and reasonable fear.
These things can then avalanche. The opening round of new-system purchases sends signals to the developers and publishers of games: is it worth struggling to learn the arcana of the new system? Is the potential payoff worth the time and money that go into generating high-definition content? Should we bother making games exclusive to one system to show off the best of what it's capable of, or should we play it safe and make a game that plays more or less identically on all the systems? Some of the earliest PS3 releases supposedly needed to sell two copies to every PS3 owner in order to make back their production investment.
The same can go for a system's online services: people don't use them because they're convoluted and empty, the company realizes that people aren't using the service and decides that's not where they want to spend their support and R&D dollars, closed circle.
Consumers may "respond to value", but value isn't necessarily evident on launch, and some aspects of that "value" aren't even developed until well into a console's life cycle. Ironically, by overestimating a console's monetary value a company like Sony can make it's real, long-term value diminish, or at least fail to flourish.