I'm basically saying the 3ds shouldn't receive these titles. They're doing terrible (except for Pokemon). Superstar saga DX would've done much better on the Switch.
I get Nintendo wants to support it, but at the same time it's costing them sales
To interject here, I think you're hitting a bit of a brick wall. You see, the reality is, as great as the 3DS titles are - a lot of them are stop-gap games. They're games to satisfy the 3DS in what is effectively it's last year of life.
A lot of these titles are remakes of older games, ports, or late western releases. The remakes are of the more niche games in their franchises, and they're not up to the standard of the Switch. I mean don't get me wrong, Samus Returns had a lot of work put into it and so did Shadows of Valentia(it's really surprising how much work was put into Valentia in fact). But they're still more rigid experiences. Hell SOV even uses the same maps as the original game, and a lot of the same outdated mechanics, just for the sake of keeping true to the original. While people like me are interested in seeing the different variations of FE gameplay, that style conflicts with what made FE so popular. It wouldn't be up to the standards of the Awakening fans waiting for the next big console iteration. Consider also that FE already has a game out on Switch, and it's getting a mainline one as early as next year. For Metroid Samus Returns ... the answer is a bit foggier, but I imagine that the Switch 2D Metroid should be original and not a remake.
Also, this site has already been over this with an earlier thread, but I think people are putting too much stock in expectations. Reality is SOV and Metriod Samus Returns are selling well, not great, but good enough. I think Nintendo, you know the actual company that cares about money, would port them on the Switch immediately if there wasn't a good reason to put them on 3DS.