I strongly agree with this and don't actually want more civilizations at this point. There are a few I'd be happy to trade, though...
Eh, my perspective on this amounts to two questions:
1) Are there very large empires or cultural regions that are still unrepresented? (Yes: Maghreb, Oman/Swahili, Pashtunstan, Burma, Bulgaria, western America)
2) Is there still unexplored design space? (Yes: more asymmetry/challenge civs, non-military unique units, group hug or collaborative civs)
As long as both questions are still "yes," I consider it a profoundly missed opportunity for the devs not to continue developing VI. As it stands, the creativity/complexity of civ designs still feels restrained from as far as it could go, and the world outside of Europe (and, somehow,
South America?) still feels underrepresented. If
this is where the devs brush off their hands and call "done!" then I'm frankly underwhelmed.
Though heaven forbid they do a public poll for the next batch of civs, because it will probably result in something looking like: Italy, Austria, Denmark, Ireland, Romania, Finland, Bohemia...and probably the Iroquois.