I didn't say "most"--I said "some"--which is the truth.
However, from the tests I have seen, single-core Yonah IS a very fast chip, faster than a G4 Mini. It depends on the task of course. But regardless, for low-end buyers, a G4 Mini was adequate power to begin with, and still is. (In fact, almost every Mac user I know has less than a 1.5Ghz G4--thanks to the long useful life of a Mac--and that includes some professionals doing graphics work.)
The point is that for SOME people, a cheaper Mac is more important than having dual processor cores. This is the model that sets the minimum entry barrier for becoming a Mac user.
So you really can't say that Core Solo is for nobody, or "embarrassing." Not many months ago, it could outrun most laptops in the world!
I'd recommend a US$499 Core Solo Mac in a hearbeat--and a lot of people (not "most") would gladly take it instead of a $599 or $699 64-bit Core 2 Duo--or even a $549 Core Duo Yonah. $500 is a magic price point in some consumers' minds, and I think Apple would do well to reach it again.
EDIT: I run my business from a machine slower than Core Solo--and I'm far from alone