Decisions with comic characters change so much that it's hard for me to care too much about any decision relating to who they are nowadays. You've got gender bending (Thor and Loki into women), race changing (in terms of skin color and alien background, from time to time), changing from a good to bad guy or bad to good guy, changing from a normal guy to a psycho, just retconning out the wazoo. So nothing seems particularly sacred anymore.
Luke Cage was essentially a glorified version of Shaft in his original incarnation. Now, he's a bit more generic from what I've seen. His identity isn't tied into black anger and social oppression in the TV show. Not sure if it is in the comic or not, but if they take that away, then it's not applicable to the other media format. Similarly, Falcon was initially a social worker working in poverty stricken areas of New York. And at one point, he was a pimp. The movie version is pretty dang far removed from that, as well. So, he loses the social relevance that the character once had. For both of these characters, at this point, the retention of the black race is more a cosmetic decision than anything else. And at that point, does it matter anymore?
Black Panther is something where you can make a stronger argument, because in the movies he is still fundamentally connected to a non-colonized African country. But I'm more concerned with changes to intrinsic personality characteristics and motivations. And there, I blame the comics as much as the movies/TV shows in a case like Luke Cage or Tony Stark (in the latter case, his movie incarnation had an effect on the comic version). One of the biggest offenders there is Nick Fury. I don't care that he's black, but I do care that he's Ultimates Fury (i.e., Samuel L. Jackson in any given role) and not the grizzled, battle hardened warrior that 616 Fury always was.