It's scary really, but then I guess there's always an element of the population that are susceptible to that kind of herd mentality and fanaticism. Apple's greatest strength isn't its products or services, it is their ability to make people believe in them enough to buy (and keep buying) overpriced status items that they want rather than need.
If we're all brutally honest for a minute, there is enough computing power in a Core2Duo-era computer running Linux, Snow Leopard or Windows 7 to do 90% of what most of us need a computer to do. Maybe the declining growth/sales of new and shiny is a symptom of people waking up to the fact they don't need to upgrade every year or even every five years.
You have a point. However, most people are not techies. They just want their stuff to work decently. Linux scares many non-techies (assuming they've even heard of it). Plus, desktop Linux doesn't have the apps that "regular" folks have heard of. There are probably more Windows 7 machines out there than Macs, so that probably supports your point. However, Windows 7 requires people to be diligent about software updates, including updates to their anti-virus software. I get at least one friend a year whose Windows machine suddenly "stops working," mainly because of malware.
The simple fact is, every brand benefits from loyal customers. That's part of what keeps a brand from becoming a commodity product. BMW has fans despite the fact that Lexus, Infiniti, and others have emulated the 3 Series formula. Burberry has fans, despite the fact that you can get a decent trench coat on Amazon.com for a fraction the cost. That's just part of life. Otherwise, there would be less incentive to make new products, I guess.
Now, regarding people buying fewer computers, that's probably because the TRUE personal computer for many people is a smartphone. We have the cult of Apple to thank for that.
Oh, and one more thing: industrial design. I'm in the IT field in the Bay Area and I was in the DC area before that. One thing I've noticed on both sides of the USA is that techies seem to under-appreciate aesthetics. However, Apple understands the value of aesthetics implicitly. One of Steve Jobs' greatest contributions to Apple was keeping Jonathan Ive and prioritizing design. People might complain about Jonny, but he has won every industrial design award there is. When people decades from now study industrial design, Jonny Ive will be in the history books along with Dieter Rams (who basically crowned Apple the successor to Braun when it comes to design), Charles & Ray Eames, and others. That's another reason why some people are so crazy about Apple, just as some people are crazy about Audi, Porsche, Bang & Olufsen and other brands.