Maybe that's because the iMac is for the price range you're looking at? The Power Macs are the "luxury" item, and are priced higher because they offer more power and more features. The iMac is for the $1200-$1600 range. It's just logical. Do you also complain that Rolls Royce doesn't offer a sub-$10K car?
And you drop 2 grand for a machine that does a whole lot more that just hold 512megs of ram and a 160GB hard drive. Or are we all back to just comparing numbers again?

Honestly, now...
Man, the complainers are out in force today.
How about think about the big picture: Apple JUST LAST WEEK announced a brand new iPod and new iMac that they have been working on. But they also found time to upgrade the PowerMac, PowerBooks, and develop new software for photos. WHAT WILL MAKE YOU ALL HAPPY??? It's like Apple can do nothing right for you so-called 'fans' of Apple.
Ok, done with rant.