Uh spoiler?Why rebuild a wrecked WWII battleship? Why not just build something new?
At least in the reboot (Space Battleship Yamato 2199) they don't literally rebuild the WWII battleship of the same name, but use the wreck as a cover. It's also not even the wreck of the original ship but a replica of it sunk as a commemoration in the 21st century.