I do think that some people say skinny naturally after a certain point. I don't ever ever ever go above 135 pounds even if I'm eating like a pig and not working out, and I'm reaching my mid 30s (had a very unhealthy year with one travelling job, back in peak shape now). For sure some would have gotten much fatter under those conditions. I think your "natural" physique is greatly determined by genetics if you take extreme training out of the equation.
Yeah Bhops Physique when he was at Middle weight was awesome (no Homo) That was prolly those most fit Trinidad has been in that picture.
For the Welterweight division, surely Tommy Hearns was impressive, even scary. Not because of his muscular definition, but his height, reach and incredibly intimidating stare. That guy looked like he really wanted to kill you in the ring (and he could). No matter how muscular Tim Bradley of Floyd looked in the ring, I would prefer facing them than Hearns.