I seem to read two quite different views of "moderate" on this thread. In one case it is a set of values that is somewhere between right and left so the positions can seem mushy to those inclined to a strict ideology. In another case it is a set of values that might be firmly to the right, but a recognition that policy is not the same as principles, and policy compromises can exist that maintain one's principles. I personally don't consider this second case "moderate" but rather an example of practical politics.
Well that's the point. People don't look or sound extreme if they can compromise. Ronald Reagan was never really viewed as an extremist by a majority of people because he did compromise, unlike Gingrich who did not in the 1990's. In the 90's, I doubt that Bob Dole was that much further to the "centre" than Gingrich, but he knew when to be pragmatic, which made him seem less extreme.
Extremists, by definition, use extraordinary methods to achieve their aims. This is what happened with the budget shutdown of 1995. Moderates on the other hand, like to try and compromise to achieve their aims. Examples at this present point are people like Harry Reid, and (on a good day) Mitch McConnell. I would class Romney as one of these as well.