It's not quite right to compare the marketing of the *Mac* with the marketing of the *Mac OS*. Indeed, if you look at the iMac pages, you see a lot of the for-the-people sort of marketing language ("technology democratized," "your life on a computer as beautiful as the ipod.")
Tiger, on the other hand, is an OS *upgrade*. Upgrades are always marketed primarily to early adopters, power users, and potential switchers. Sure, in the old days, Apple pretty much sold one thing: a Mac. Now, there are clearly different products, some hardware, some software, that are targeted at different sorts of customers.
"The Mac, we were told, was the computer for the rest of us."
And it still is. Don't conflate the positioning of *Mac hardware* products with the *Mac OS* product.
Macintosh: The Computer for the Best of Us?