Well, it's a teaser trailer for the sixth sequel in a well known franchise, I think mostly everyone in the target audience knows what the game is about and trailer is just to build hype among people who would be hyped even if it just said "Civ VII confirmed".

It's explicitly a teaser trailer. And what do we need to know really? It's a new Civ: they'll update the graphics, fiddle with the mechanics, and we'll have to wait and see if the changes work.

I think the key is “teaser”. There is a lot of emphasis in building awareness very early on, rather than releasing videos of a completed project.

Expect more details in future trailers