Not all bathrooms have to be cold and sterile to be modern. Take this example, a contemporary master bathroom by Rusal Construction, The space is warm, inviting, welcoming. We still have the focus on geometrical shapes (in this case, egg-like shapes via the sink and tub), a simple color scheme (warm neutrals), and minimal decorative elements. Wood and stone (or convincing look-alikes) are typical modern features.
This one definitely has more decoration than most modern bathrooms, but the decorative items are simple, with basic shapes: empty frames, paddles, and candles.