So what? Those movies are in high definition which means they will be occupying a lot of disk space.
What it DOESN'T mean is that the game sucks, or by the same account, that it is brilliant, for only using up 6.8 GB. That's a very limited thought process.
Past Final Fantasies of the PS 1 and 2 era also used a lot of disk space for their movies and nobody complained, quite the conrtary.
It's about high fucking time people stop pissing all over Final Fantasy just because the JRPG era is over and all they want now is shooter-o-rama.