I must say, I'm surprised at the blatant dismissal of the wallpaper in this stateroom. It is important to remember that the immediate reaction of our eyes today must be tempered with how it was perceived in its era.
This new stateroom clearly illustrates strong elements of Cubism, in addition to early Art Deco motifs fresh from the 1925 Paris Expo. For its era, especially on a ship, this room was exceptionally modern and would have caused quite a reaction (either positive or negative) in those who viewed it at the time. Negative reactions came from those who didn't like the new "Modern" movement, preferring instead the more familiar styles of previous centuries. Others embraced this new look wholeheartedly for its functionalism, "movement", and clean lines.
The wallpaper in this room is a perfect example of early Deco design, and suits the room very well. It unifies the elements of the angular furnishings for a decisive, cohesive "Modern" look. Plain painted walls, wood paneled walls, or floral wallpaper sprays (the other au courant wall treatment choices) would not have had this same unifying affect.
Aesthetics are, of course, subjective, but only to a point. "Not in my house" may be a valid perspective in viewing this room today, but at that time, the style was new, hot, and very now.
Few other ships in 1927-1928 would have offered passengers such modern (and popular) style. Perhaps White Star was trying to lure passengers who might otherwise be tempted by CGT's stunning new Deco Ile de France?