When I started using Apple hardware, the CPUs ran at 1MHz (Apple ][).
Let's see - it was 10 years ago when Sun released the 170MHz UltraSPARC CPU, for example. 'Bout the same time, the 200MHz Pentium was around, and Apple had 604e systems running at 150Mhz.
The trouble with the 170Mhz boost is that it's not really worth it in my mind. There is no way you're going to really feel a difference between 2.0Ghz and 2.33GHz (for example). That's all of a 16.5% boost, big deal - If my brain is working, that means a 60-second task would take 55.2 seconds. Certainly nothing like going from a 16MHz Mac IIx to a 40MHz Mac IIfx.
But, there will always be people wanting to pay for the "big number".