Pretty much what ryodi said.
I have Pokemon in my Bank from the GBA era. The idea that I won't (possibly) be able to carry them forward because of dev time reasons when we've already been waiting a long time is incredibly disappointing to me. Having them sat in Bank or Home (FWIW another issue for me; when Bank was developed it was touted as the definitive one-stop-shop for cross-generational 'mon. Unfortunately this apparently meant just the generations we had there and then) is just going to split my collection in frustrating and unnecessary ways.
The challenge of catching them all for new players is, uh, not really something normal people do! Every game for a long time has recommended completing its local version of the Pokedex for a cool reward, but stops short of recommending people go for a full national dex (this means every Pokemon ever) as there's no reward for it but personal satisfaction. You will never come to Pokemon as a new player and then have the situation of "well, 1 down, 900 to go!" So, for those players who have done that... well, fuck you, in short, it feels like.