I'd also like to bring up the fact that the Queen grew up during World War II, when clothing, food and other necessities were rationed. Because of these austere measures Her Majesty doesn't live extravagantly (relatively speaking since she is a head of state).
About that piano....it was originally made for Queen Victoria in 1856 by S&P Erard, according to RCT's website. It features gilded and painted surfaces. Yes, it looks like it might belong in Trump Tower, but it's a historical piece.
If you missed the Queen's Christmas broadcast yesterday, give it a listen below, gold piano and all.