What everyone seems to be forgetting is that we are talking about Macs...not PCs. For most people, Macs are as much about style as ease of use, reliability, etc. That is why Apple needn't worry about introducing a G5 eMac so soon after the G5 iMac...because so many people will continue to prefer the iMac due to its unsurpassed style. Apple knows this; that is why they had no qualms about keeping the specs of the G4 versions of each machine so close, to the point that the eMac surpassed the iMac for a time!
Plus, style is not the only thing that will keep the iMacs selling....lets not forget the space-saving design that Apple has perfected with the iMac. Space may not be a concern for everyone, but anyone who has lived in a college dorm or townhouse knows how much every inch matters. Plus, the base iMac now includes a widescreen 17" LCD, which not only is larger and easier on the eyes than the eMac's 17" CRT, but consumes far less electricity, which is a godsend to those running multiple machines and the enviromentally concious.
Finally, a G5 eMac is something of a nessessity for Apple in all markets. An incresing number of businesses and governments are looking at Macs, and these customers demand as much choice as possible, especially when budgets are concerned. Then there is the education market, which, despite being very budget concious, still demands the best bang for its buck (and right now, many of them correctly see this as getting a G5 system). Finally, there is the consumer market, which has been trained by the wintel world to look purely at specs. Imagine, a possible switcher goes to apple.com and sees a last-generation G4 Mac going for $800, and then goes to dell.com and sees (what they percieve to be a cutting edge) Pentium 4 for $800, they are going to buy the Dell, because it is natural to want the cutting edge (its the same reason that many people, as was pointed out before, hate to see thier recently-purchased systems surpassed).