I don't think it was wrong for them to make another game for 3DS. There's still a huge install base, and I think a lot of people will probably buy this game too.
I think what I was (and maybe a lot of people were) expecting for another 3DS game was a DP remake. That would have been a great sendoff on the 3DS, and then you can put your next generation or sequels on the brand new console.
But I suppose in some ways, the games are tied to handheld, and even though the Switch can be that, I'm not sure the people at Game Freak see it that way.
I wasn't even expecting them to pull another BW2 again but here we are, and I'm honestly a bit disappointed. I'd like to see them do something new and refreshing but....I guess we'll see.
This was a super weird time for them to show it off. This direct should have been just Pokken and GS Virtual Console and then you drop a bigger trailer/reveal during E3. But maybe E3 is gonna be all Switch so that could have been why?