The size matters. The hilt of the gunblade is the handle of a gun. It is not made or capable of supporting a sword the size, especially how you hold a gun.
This is essentially equivalent to arguing Cloud's sword is too big. Oversized weapons is kind of par for the course. It's not special because it's an oversized gun blade.
This is a terrible thread and I'm not saying that because of the drastically wrong title. Everyone is wrong and right at the same time.