Yeah, seriously, what's up with that? Also, if they have to go there and use aliens to allegorise topics like colonialism and race, my gut-feeling says that movies in which aliens colonise human planets to show the inhumanity of this kind of behaviour would be somewhat more appropriate. Well, just as long as the resulting movies don't involve a huge epic final battle in which male white US soldiers lead a rag-tag army of POC locals into battle.
Not that I think that allegories of these kinds do much good, anyway.