The powder room is small. It does not have to work all day. Nobody sleeps there or cooks in it. It exists for a single function and takes up roughly forty square feet of your home. These constraints, which might seem limiting, are actually what make the powder room the most interesting room to design in a luxury residence.
Because it is small and has low functional requirements, it can absorb a level of risk and specificity that would be too much for a room you spend hours in. A powder room that is genuinely surprising, that stops guests, that has something to say, is one of the most effective design moves in a high-end home. I always encourage clients to push harder here than anywhere else in the house.