I would have that expectation.With the current developments, I guess we shouldn't have any expectations though. But yeah in all seriousness, I also had the expectation for Sword and Shield. I expect every core game to atleast have all Pokémon programmed in or atleast have the oppertunity to DLC or buy patches to have them programmed in if they indeed had time limit and never done it before. I have done playthroughs with various Pokémon in every gen, so I can adapt to the limitations but at a certain point you have been through all the potential options you enjoy. Ruby and Sapphire also had a limited roster, but was expanded with Colloseum, XD, Fire red and Leaf Green and all Pokémon were be able to be traded to each game, even if they were not available in those games. Sun, Moon, Ultra Sun and Ultra Moon also only had no official National dex, only if you connected it to Bank, but still all Mon were programmed in and if you played the Virtual Console or sent over your mon from past games through Bank, you still could play with them.
My personal problem is not even the limited roster itself, but more that it feels a bit stupid at this point in time? That is why I have that expectation that every mon will be programmed in aswell. Every new console gives more oppertunities and more space, but Pokémon as franchise have been less than innovative and for all I know also never used the full capacity or potential of the consoles they were featured on. I get development costs time and energy and they probably had problems with time restrictions etc. But this is more a descision that would have made sense in Generation 5. We had a complete NEW set of monsters, with every other gen excluded. Every gen forward could have been an altered roster and we basically already would have been used to it by now.
It just feels odd to me personally that Gen 8 is the point they start these limited rosters, especially since it is the follow up generation to the generation where we could sent over Pokémon from every single game from Red/Blue/Yellow to Omega Ruby and Aplha Sapphire. Gamefreak has made us so used to be able to have everything ready and together that this descisions gives competitive players, players like me who do various playthroughs etc. a sort of panick attack since we are for the first time ever limited, since they basically already said that this is the new policy for the future aswell, so no game for all we know will ever have al Pokémon programmed into them.
It is is what it is at this point, and I keep being curious to see what more will be revealed up until the games will be released. I just wish the descision itself woulf have had a little more sense and a little more information. It;s like they dropped a bomb and just left (for now)