Well, that "sky" doesn't feel like it was shot in the early '70s at all. They should've just left it. Damn it, George ...
That said, it actually doesn't bother me that much. It's one shot and the change actually makes sense, unlike many in THX 1138 and the Star Wars movies. But I still wish it hadn't been changed, just like I wish they hadn't erased the cobra's reflection in Raiders of the Lost Ark.