I have no real problem with this, Jordan is a great actor as evidenced by his roles in both The Wire and Friday Night Lights, and I don't personally believe that any of the FF are so-called 'race-specific' characters (maybe Thing, his overt Judaism is a recent thing, but it was always intended and since he is Kirby's avatar, it could be seen as inappropriate to have him not be Jewish, but of course, nobody seems to have a problem with non-Jews playing Jews, and also, Thing is orange, not any real-life skin complexion).
But this does raise the question of what is a 'race-specific' character? I'd argue that there's not very many of them really. Black Panther as an African King is one (and probably any other character with 'Black' in their name except Black Bolt, Luke Cage and Iron Fist as a black guy/white guy duo, and maybe Storm, but other than that... Captain America as a product of his time-period could only be white... hmm...
It is interesting that most white characters are seen as not particularly tied to their race, but most minority characters are, is this because of poor writing making minority characters tokens? Is it because the white experience is the largest, most common one and therefore not deemed important or something worth exploring? Is it because of the dreaded reverse-racism?
This is a complex issue, maybe I'll write another controversial Tumblr-post... :p