They had no legitimate reason to cut Pokémon from the dex, especially with how much data is still in the game. If they stood behind their excuses they wouldn't be reintroducing cut Pokémon back in. They'd only release new Pokémon. Which they should be doing because the expansion pass was $30, half the price of a new game.
--------------------- MERGED ---------------------------
I wouldn't call this an AAA game. Even remotely. The game is still has the amount of content of a handheld game. The only real improvement is the wild area and overworld encounters. And yeah, reusing models saves them a ton of work. So does the crappy animations in the game. The game is something that could've released on last gen consoles or probably even Vita, the game is a glorified handheld game on a glorified handheld. The new content we've seen looks pitiful. I wouldn't have even bought the DLC if I actually thought people would be willing to help out people who don't have it. I'll sure trade spares of new and returning 'mons to people who don't have it. Third versions and sequels usually more actual story content too, this is just mostly cut content, with a bit of the normal postgame we get in a third version, but without the new story content. If the confirmed new mons are the only ones we're getting, we're basically getting something like what we got in Ultra Sun/Moon but without the new story stuff that game had. So 30 bucks for a possibly 6 new mons and a some new formes. Fantastic deal.
Source
