Hi Raul,
I agree with what you said 100%. Maybe I should have said it like this - the job of amplifying a .4mv signal (MC) well is much harder than amplifying a 4.0mv signal (MM) well. The phono stages that can really do a great job with the low voltage MC signal are usually much more expensive than a phono stage that has great MM capability only.
That being said, unless the person has told us what phono stage is being used, I tend to assume that a person just getting into serious analog doesn't have a Manley Steelhead laying around, but rather is likely using the phono inputs of a stereo receiver or maybe a modest phono amp. In that environment, I think a good MM cart can deliver much better results.
Or to say it another way, IMHO it is better to have a great phono amp and a good cart than to have a great cart and a good phono amp.
Cheers.