I doubt that they would have been slammed too much about stealing from Galactica. If the ships looked different, and the names were different. I believe it was said they were going with a single planet rather than 12 colonies at one point, which would also have helped. Man's creation comes back to kill them to the near point of extinction, isn't exactly Battlestar, not by a longshot. Tons of series and sci-fi have a holocaust of some kind that forces "man" off their original world, but they aren't thought of as clones of Battlestar. Since most of the "villains" look human, and if they had gone with a non-cylon looking metal villain (they are practically there anyway) I just dont' think it would have been there. Different names, different look, different concept = different show.