Yeah that's a weird choice. Todd Howard said that the game has performed upwards of 60fps in some places, but they made the choice to lock it down to 30fps on console for full graphical fidelity.
I get that not everyone has a TV that supports VRR, but they should be able to programmatically check what the xbox is currently supporting. If it is a Series-X and does support VRR they should be able to unlock FPS to up-to 60. I mean even 40fps on the steamdeck is surprisingly good, whereas 30 can be really jarring. Or give a choice to the user, 4k@30 or 1440p@60 with VRR.