Well, I'd tend to think that it is because the most all-around capable transducers tend to be the most even sounding, hence free of colorations. As I think most of us know, certain colorations can enhance the listening experience with certain music, even if it just effectively EQ'ing. Hence the reason that many of the very best headphones are not all-arounders, they have colorations which put them at an advantage with some music, and a disadvantage with others.
And once you reach a certain (high) level of objective performance (detail, etc.) it all really just comes down to personal preference, and the colorations (or lack thereof) all have their own places.