Part 5 is fabulous hetero (MCs try to look at Trish's tits).
Part 6 is hetero (Anasui is a retcon).
Part 7 is brokeback hetero (both MCs have sex with women).
Part 8 is overtly hetero (literal rapebait femC).
The 80s (the decade when big manly characters in pop culture were at the peak of their popularity) ended. Toshiyuki simply decided to go with the times and go from muscular baras to slim, fabulous bishounens. He was always a fan of fashion and most fashion models in the world are slim, beautiful, and androgynous men (especially in Japan).
>>283683551 (OP)
Tetsuo Hara of Hokuto no Ken, which has very similar artstyle, can still draw more or less in same way for 40 years now, even when he switched to digital coloring, unlike Araki.
I guess stagnation can be a good thing sometimes.
>>283683551 (OP)
Part 7 and up is a mixed bag for me, I like the way araki draws faces but everyone looks the same. He had more variety in the earlier parts.