You have to consider the fact that only a very very small portion of the CPU market is made up of Overclockers. To the average joe, who doesn't even know what a BIOS is, BUYING extra CPU speed makes perfect sense in their mind. They're simply adding stepping stones for the users that want to upgrade. I'd say their market is working wonders right now. If you have 2 CPU's $75 and $150, the difference is very distinct, and people will most certainly be drawn to the cheaper of the 2. But if you throw in some 'stepping stones' $75, $90, $115, $135, $150; the line blurs, and people start to talk themselves into buying a more expensive chip. "Oh... well I can get an upgrade for only $15 more... ok"
... Then there is the chance occasion, they come here and find out... they're all the same chip