Whenever I ask people which princess they like its either; Diana, Kate, Grace, Letizia, Victoria and Maxima. I understand Caroline is not of this generation but neither was Diana or Grace but they still are recognized. I've been interested in the Monaco family for a while and Caroline really took things under control after her mother's untimely death. As First Lady she did a great job esp in the 80s. Started the Ballet company and she has done work with ADMADE which helps unfortunate children. Why is she underrated?
I don't believe that she's "underrated" by anyone especially the people of Monaco. IMO we should recognize that the women that you mentioned are also decades younger plus they're or were the current or future Queen Regnant (Victoria) or Queen/Princess Consorts (Catherine, Grace,Letizia, Maxima) of their respective nations. Or in Diana's case she was meant to be the future Queen Consort.
Also I don't believe that Caroline truly wants the media attention that the other women receive.