Another thing to note is that from what I remember, the first Hamsho fight represented the first million-dollar payday of Marvin's career, so to say it wasn't lucrative is plain old not knowing what the hell you're talking about. That was a huge milestone for him. A million back in 1981 meant something.
I agree. You could say he would have done well from 1890-1987. If you want to downgrade him a bit, he fought a few smaller guys in legacy fights ( Duran, Hearns, Leonard ), wasn't the most skilled fighter around, and for some reason had it on cruise control in some fights.
Do you realize the 168 division was considered a joke when it started then. Only the IBF recognized it until 1987. No one, and I mean No one was calling for Hagler to fight for that title. Sutherland and Park were retreads who had failed in their respective divisions. You probably weren't born yet so I understand your confusion.
Moving from 160 to 175 would have been a big jump. at 5/9 he would have been at a huge height and reach disadvantage to the 6/3 Spinks. And the 168 division was a joke when Hagler reigned at 160 lbs. The only money option above 160 lbs would have been Spinks and that would have been a huge risk against a much bigger guy in his prime. I think Hagler did the right thing staying at 160 lbs.
Though Spinks at most 6' 2 1/2" I agree completely. Spinks was a top ATG at LHW, prime then, & fought at up to 212 & lean as a HW. Hagler was one of the very greatest ever, but that would have been too much to expect from anyone.