The first series is ALSO called Pocket Monsters, so that's confusing and PM2019 is just awkward. The series is set in Kanto, but it's still the anime counterpart to the games and Galar is the most visited region so far.
I agree, while I'm sure its weird to have it be SS, this is the 8th generation of anime, and will heavily feature 8th generation stuff so it just makes sense to focus on the primary introduction to the 8th generation which is Sword and Shield. Besides I don't know much it matters, 1st and 2nd generation were referred to as just simply EP, and 3rd generation was referred to as AG (advance Generation). It was only from 4th generation on that the system of separating generations they went with the games. So DP, BW, XY, SM, and now SS.
Honestly I would complain more about why the hell they insisted on calling it "Pocket Monsters" to begin with. I mean they went with "Best Wishes" for Black and White, they couldn't come up with something other than: Well we couldn't think of anything.......POCKET MONSTERS!!!!! 2019!!!!!!! Because that's when it'll first air!!!!!!!
Sure nothing really fits the SS. But they could've gone with Pokemon World instead of: Pocket Monsters (2019).
On top of that who the hell knows what 9th generation anime is going to look like. Will it be a direct continuation of Pocket Monsters (2019), only it's no longer Go and Koharu but other characters (perhaps Ash will intern in the 9th generation region as a battler reseacher). Will Ash even be a thing at this point?