I think the guy who passed away was pretty big. I think the actors of old were bigger.I've never paid attention to it, but to be honest black dicks in jav aren't big at all (comparing with western porn standards). It's hard to tell because the mosaics but girls are barely able to give a two hand handjob
I suppose the interracial thing is more about the excitement of watching 2 100kg black guys fucking a 40 kg japanese girl. Or the reason is other? Maybe the lack of black actors or japanese actresses not being prepared for really big dicks.
I think one of the bald guys they don't use often is big enough for the fantasy. The two bigger guys aren't that impressive to me.