Considering that we have no recorded evidence of what singers sounded like in Bellini's day, and in fact have no entirely faithful recordings of any singer prior to the introduction of electrical recording in the interwar 20th century, I take all statements and judgments about the sounds of voices we can't hear advisedly. I'd also point out that much of the language we use to describe voices is metaphorical. I was thinking just this morning of what I said yesterday about the late recordings of Ferdinand Frantz; I referred to his sound as "heavy and opaque," and even as I wrote that I was asking myself how a sound can be either of those things. Literally, of course, it can't.
No doubt Florez makes a sound that's more "shallow" and "constricted" than Corelli's. I'm not sure what he should do to "correct" that, but it seems not to have led to any sort of breakdown in his ability to perform opera, and I find assertions to the effect that he doesn't have a voice for opera more expressions of taste than anything else. Corelli's "open and resonant" sound may be admirably loud and sensually exciting to some people (though it's never done much for me), but it didn't ensure that he wouldn't make hash out of quite a bit of music. For some musicians like me, what a singer does with a phrase can matter more than whether his voice is impressive physically.
The sort of sound considered desirable for any kind of music, and the vocal manipulations required to produce it, differ greatly among the many styles of music. What sort of sound we favor is determined as much by taste and tradition as by its adequacy in sustaining and projecting music in a given style. If an opera singer has the range, flexibility, and dynamic control to make good music in some operatic repertoire, more power to him.
As my mother used to say, "Name your poison."