From what was posted on Robert Hewitt Wolfe, is that they tried to do some diversity, it just back then, they didn't get any pushback on diversity like now. Progress times times sometimes, but we can't judge the past by current standards.
I remember watching 60's mission impossible, and they had Lenonard Nimoy play an Asian character! They just didn't care at all back then. ( Think also James Bond, Done the same with Sean Connery) So, am happy its trending to being fixed, but its not there yet.
I guarantee there were plenty of Asian Americans back then that did care. Same with Indigenous Peoples when they saw someone non-native 'dressed up' as one of them on countless tv shows and movies. Black Face went over well for the white audiences before that. I'm sure people of African descent didn't care for that at all.
So when I read your sentence of "They just didn't care at all back then" I interpret 'they' as white people, the powers that be, etc...Non-white folks did care. There's a quick and powerful scene at the beginning of Dragon: The Bruce Lee Story. Lee is on a date with future wife Linda and they are watching Breakfast At Tiffany's, a Hollywood classic. I'm sure the general white audience found this particular clip funny and at the very least not objectionable. But to someone different....
https://criticalmediaproject.org/dragon-the-bruce-lee-story-breakfast-at-tiffanys/
I agree with your top portion about not getting any pushback back then but we also have to understand that issue within historical/cultural context of racial dynamics. Non-white folks barely had any voice back then.