Making the PC omniscient so they can fight baddies in a 360 degree circle and see around corners might make the game more fun/easier to play/generally more pleasant, but those things aren't the same as immersion. It means to put something into another thing, like wrapping the world around a player's perspective in the case of FPP literally putting the game world around the player. Immersion does not mean enjoyable features, dynamic dialogue, beautiful cinematics, or intuitive controls, although those are important aspects of game design so can we just stop using "immersion" as a catch all for whatever we prefer and instead say specifically the what's and why's of what we want?