Jvr, it would not be correct for anyone to make an across-the-board statement that MC cartridges are better sounding than non-MC cartridges. There are many MC cartridges that are wonderful in the $2000 and over price range. There also are many MC cartridges that I personally could not tolerate living with regardless of price.
In my case, I've always used Grado cartridges (non-MC) and I'm very particular about vinyl playback - vinyl is my primary source. There are certainly other good choices, but for me the Grados just do exceedingly well many of those things that I value in sound reproduction. For example, all of the Grado cartridges get the mid-range tonality right. As one moves up the Grado line in price, there is a general pattern of obtaining greater neutrality, quickness, resolution and high frequency delicacy and extension. In the current Grado line-up, I like and use the Reference "Reference". Would I chose a MC cartridge over a Grado? If I were willing to spend twice as much or more, yes. A Helicon MC is a better cartridge.
With respect to amplification for the cartridge, the key factor is the cartridge output - not whether it is MC or non-MC. There are both low-output and high-output MC cartridges. There are also a few very low output non-MC cartridges.
Simplistically stated, the reason for making cartridges with lower output is that the the current generating components can be smaller and lighter (there can be fewer coils of wire in the "moving coil"), and with smaller and ligher components a designer can often create a cartridge that is more refined in tonal definition, quickness, and delicacy. This is not universally accomplished, of course.
Historically, most of the better MC cartridges have less than 0.8mv output. (Some are low as .2mv which becomes exceedingly challenging.) Most non-MC phono stages can handle cartridges of 1.0mv or greater. Some can handle a few tenths of a mv lower. But a good rule of thumb is to expect good results at 1.25mv or greater. All will depend on the characteristics of the particular preamp.
I'm sure there are some Audiogon readers who can share with us which are some of the better higher output MC cartridges.
Just to keep the record straight: the Grado Reference line is currently offered at 1.5mv. This is going to change. The new line will operate at 0.5mv moving clearly into the low output camp that has long been the sole domain of MC cartridges.