I am actually not surprised, all the arab first ladies are popular, but most of them not loved.
Princess Lalla Salma is loved because she came from common people, she has a warm and lovely personality, she has the image of the arab intelligent woman who made difficult studies for her own and not thanks to money of papa or so, and she doesn't make a lot of fuss around her on medias.
I have a jordanian friend, and when he knew my interest to Royals, he talked to me about princes Lalla Salma and told me she is his perefered arab first lady, I am surprised that they don't like Queen Noor in Jordan.