Here's another reason: many if not most people don't keep up with Apple technology. As far as they're concerned, Apple hasn't hit 1GHz in anything. One friend of mine (who knew a week in advance that 3.4GHz P4's were coming out) still thinks the Flower Power iMac is the most up-to-date. There's not enough actual product advertising from Apple; the new PowerBook ad with Verne Troyer is the first one I've seen in months. All the rest have been switch ads. Most people I know have never even heard of the eMac, even IT guys. Here's the typical perception of Apple's lineup:
PowerMacs: 733MHz DA, not even QS. Most have no idea they've broken 1GHz. The only good part of this perception is that they do realize PMs have a DVD burner.
iMac: half the people know of the LCD iMac, and call it a lamp, and are also completely unaware of the superdrive or 17" LCD. The rest know only up to either the Blueberry/Strawberry/Grape/Lime/Tangerine iMac DV's, or possibly the Flower Power.
iBook: clamshell tangerine and blueberry, with only people who know someone who has another one knowing about any others.
Ti/AlBook: This is the only one people really know about and respect, if only for the screen size.
eMac: "A what-Mac?" You get the idea.
XServe: only IT people have heard of it. While they're impressed with certain features, they just write it off as "just another too-slow Mac. I mean, it doesn't even have DDR, or a UNIX OS." At this point, I quietly remind them that it does, to which I get a mumbled response. I agree, people don't like change.
iPod: this is the one thing they all, or almost all, know about. But they just say it's too expensive, or can't carry data, or can only hold half the songs of their other one with the same capacity. Apple needs to advertise more than 4000 songs, even if it means calling it a 3 minute song at 128kbps. That's what most manufacturers advertise at anyway. Or if they don't do that, they should make the fine print about a 4 minute song at 160kbps much larger.
Software: many if not most people have no idea OS X is a UNIX, if they know it exists at all. More than half the people I know think Office is Windows-only, and are shocked and amazed when I open Office v.X under OS X. Also, people, even IT people have no idea how much cheaper X or X Server is as compared to XP Home or Pro, especially when comparing unlimited-user licenses. After all, if MS makes you pay $X thousand a year, they figure Apple does too.
Speed: Nobody cares about AltiVec, all that matters is bus speed (for geeks) and processor speed (for everybody else). That 'everybody else' doesn't care about video cards, or network speed, or even, in most cases, RAM or HD space. A friend of mine just bought an HP with 128MB RAM, and a 40 GB HD, no video card (just integrated graphics) and a 10Base/T ethernet connection, all because it came with a free 15" CRT, and a free cheap printer (ink and paper not included), and was $1100 when all was said and done. They didn't even realize that it came with a DVD/CDRW. IMHO, it was a mistake for Apple to discontinue their CRT line. People just don't care about LCD vs. CRT, especially Joe Consumer. They care about price and freebees. Give em a free 15" monitor and printer, for less than $1200, and people will come flocking. The best way to do this, would be to much more heavily advertise the classic iMac, preferably with a better, possibly even x86, processor, and give away a printer with it. Also give it a Radeon for QE graphics, and it would sell like hotcakes.