I don't think it's a question of mixing up wants with needs, I think it's a problem of having a need that doesn't have a solution. Think back to Maslowe; once physical safety is guaranteed, what happens next?

I think almost everyone, even consumers, understands that they're uselessly consuming and that it's not sustainable and that they don't need what they're buying. But even if we somehow stopped the consumerism, stopped passively absorbing information and desires from mass media, stopped buying things we don't really even want, that would necessitate a ready alternative outlet for those kinds of desires and impulses. And that outlet doesn't yet exist en masse; you would need to create some sort of philosophy utopia for it to be possible, where people are able to quiet that raging brain that says "Give me more".

The major reasons for shopping sprees and "retail therapy" are psychological and emotional. If we stopped consumerism, we not only need a new economic system based on something other than growth, but an entirely new entertainment system, which is considerably more difficult, particularly in a non-religious world. I think Boredom is a more persistent and difficult problem than people believe, and has sculpted our society far more than any innate desire to simply consume. Modernizing the world has led to Boredom in unprecedented amounts; changing the economy away from consumerism could actually be dangerous.

We aren't psychologically prepared for a world where the television stops feeding us new things, the internet only connects to good, wholesome material , no new video games come out, etc. etc., because of the fundamental problem of human life: what can we possibly do all day with these oversized, ever-thirsty brains? Furthermore, as far as games and entertainment, who would be deciding what is a "need" and what is a "want"?