You forget the fact that we've been waiting for literal years.

I'm amused at the idea that Final Fantasy Versus XIII was used as an example, since in-between Final Fantasy XIII and Final Fantasy XV we got:

Final Fantasy XIV
Final Fantasy: The 4 Heroes of Light
Dissidia Final Fantasy
Final Fantasy Type-0
Final Fantasy XIII-2
Bravely Default
Theaterhythm Final Fantasy
Final Fantasy XIV A Realm Reborn
Lightning Returns
Theatrhythm: Curtain Call
Final Fantasy Agito
Final Fantasy Explorers
Mobius Final Fantasy
Final Fantasy XIV: Heavensward
Final Fantasy: Brave Exvius
Bravely Second: End Layer
World of Final Fantasy

If Metroid had gotten that many games in between… Well, I'd be a happy man for starters.