Where are the battle facilities? Not just Frontier ones but other good ones like the Black Tower/White Treehollow.
Where are the following Pokémon?
Why aren't there enough dungeons and why are the ones that exist not large and complex enough?
Where is the medal system?
Where is the DexNav?
Where is the VS Seeker?
Where is the PSS?
Where are the Secret Bases or an alternative like the Platinum villa?
Where are the seasons?
Where are the fun minigames? Remember HGSS had at least 10 of those, Mantine Surfing and Ultra Warp Ride are just two.