Taking Rivvon's post into consideration here, there's something to be said about the Pokemon being Sun & Moon's "selling points", here. I have to consider really hard whether or not this means the other features of Sun & Moon aren't as important as the Pokemon themselves, or whether this is intentional and they just want to keep the features secret for whatever other reason. I mean, it would be concerning to a large degree if the other features of Sun & Moon aren't what we expected them to be, sure, but... I dunno, in this case, I'm very careful about seeing this with a glass half empty perspective. We're two months away from release and we still have no new information about Lillie, nothing about Guzma or Plumeria's background, nothing about the Rotom-Dex, heck nothing about the region itself... does that automatically imply that these characters (or areas), despite being introduced quite a while back (more recently for the evil team leaders), aren't necessarily as much of a selling point as the Pokemon themselves?
I'm willing to go as far as to say that TPC is just trying for a different marketing tactic. Perhaps we're having a Pokedex so massive that all they can fit in their advertising is a buttload of Pokemon per reveal. This seems silly, but it's a guess, nonetheless. There's also the perspective to consider that just because something isn't sharing a spotlight with something else, doesn't mean it'll end up disappointing.