Re: Coloratura: Why only sopranos & mezzo-sopranos?

Among basses, Ramey, Pinza, Plancon, and to some extent, Pasero, were
proficient at coloratura;  Many tenors, likewise - particularly in some
oratorio parts and the Jewish Cantorial tradition, the latter in which
tenors were and still are most popularly deployed. The few countertenors
I've heard had remarkable coloratura technique.  OTOH, Baritones, except
for Cantorial repertory, seem to be seldom called upon to use coloratura
in performance.   - Bass-baritones, even less-often. 
(Not sure why this is so.)

Leonard Tillman