Soul Reaver 2 is a much less detailed game than Metroid Prime 2, but it still kind of hurts knowing that my biggest problem with the game was not a technical necessity
Metroid Prime 2 is a better game than Soul Reaver 2 imo, the realm switching is basically the one thing SR2 does better gameplay-wise.
For context, Soul Reaver 2 is a 2001 PS2 game that also has a main gimmick of switching between two near identical versions of the game world (so does Soul Reaver 1, but I wanted another 6th gen game for comparison). The Soul Reaver games allow you to switch to the Spectral Realm at any time, though you need a portal to switch to the Material Realm (which are frequent, at least one in every room). The two realms have different enemies and allow for the use of different abilities, and the geometry literally warps to allow paths otherwise untakable. All with basically no load times.
Of course this kind of consideration would have needed to been done in the earliest stages, the final Metroid Prime 2 is based around only being able to travel via portals. You'd probably also need to make the game less detailed to account for loading in the assets of both worlds at once. But my main problem with Prime 2 is how much needing to backtrack to a portal breaks the pace of the game, and it nags at my mind when I replay it.