A fully spatial hub can add a lot: stronger sense of place, pacing between runs, more world presence, and room for social or training-oriented interactions. At the same time, we do not want core player actions to become slower just because they are wrapped in a 3D space.
Because of that, we are currently leaning toward a hybrid approach: keeping the parts that benefit from physical presence in the 3D hub, while moving routine, high-frequency actions into UI. For us, the goal is not to choose between immersion and usability, but to find the point where both can support each other.
If a hub works well, it feels like part of the game. If it works poorly, it becomes one more layer between the player and the next run.