I explained the Sal Buscemasance a while ago. His 70’s to mid 80’s stuff was classic Marvel house style at the time. And he had some really nice runs on books like the Defenders, Hulk, Rom, Captain America and Spectacular Spider-Man. He also had the New Mutants for a while. He was the comic artist equivalent of the 32-year-old outfielder who regularly hits .275, 18 hone runs and 80 rbi - and plays a solid right field. The guy every team likes, but is constantly trying to replace with a hot young prospect. He just did the job at a solid professional level of quality, and did it on deadline.
I think people just appreciate the classic look of a 70’s to mid-80’s Buscema page (not a fan of his Image style era 90’s stuff). It’s not esoteric, or transcendent. It’s just representative of a great era in Marvel comics that collectors look back upon with fondness.