2.0 system installations are frequently sub-optimal, let alone anything with more jiggly bits. Corners, angles of speakers to walls, proximity of speakers to walls/obstacles, height of the speakers (for higher frequencies) all colour the perceived sound. If you have curtains in the room, the experience will be different when they are drawn. If your mother-in-law is sitting in the corner, the experience will be affected, although that's probably not physics.
Just enjoy the story of the film/show/programme. Oh bugger, that's where they've skimped.