Trivia: Alfred Hitchcock wanted the film to look as natural as possible, with the camera at eye level with the actors. Since movie cameras were large (especially 3D cameras), Hitch had a small trench built into the soundstage floor, so that the camera lens was, roughly, at eye level.
Trivia: This was filmed in 3-D, but was not originally released in 3-D. It wasn't until after Hitchcock died that it was released in its original 3-D form.
Trivia: Alfred Hitchcock's cameo in this film is one of the harder ones to spot: he appears in the photograph of Tony and Lesgate's Cambridge class reunion.
Chosen answer: It's mostly so the audience can see more of Tony's underlying character. This is Margo's bed, and Tony wanted it separate from the bedroom that they shared as husband and wife. Tony is "emotionally divorcing" himself from Margo as he is about to start a new life as a single man. Leaving the bed in the bedroom would serve as a reminder of his guilt in framing his innocent wife for a murder she did not commit. The bed is likely parked there until he can get rid of it.
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