I have always liked Kate (and to a degree, William). However, I too think this holiday is a massive mistake on their part...
In the past 12 months they've had 3 vacations. 1 week at a ski resort (after William's six-week stint in the Falklands) 3 days in France, and this trip to Mustique.
Prince Harry, Beatrice and Eugenie have all taken plenty of vacations to exclusive ski-resorts and sun-drenched villas, yet I don't hear complaints about that.
I think calling Kate a "glorified dummy", is pretty harsh. If people see Kate as just a clotheshorse, then that's on them. There has been plenty of information about her charity work, but the media chooses to focus on the superficial. They do the same with other royals. I hear more about their fashion choices, than I do about any charity work.
I've never gotten the idea that William resents his position. I think he and Harry have disdain for the media (Harry recently made his feelings known), but I don't sense any resentment for their position. Doubts, maybe. But I don't know any person that doesn't have doubts about their future.
People keeep clamoring for William to quit the RAF and take on full-time royal duties, without realizing that he and Harry think of their military careers as public duty. In his recent interview, Harry said that he and William believe their miltary careers are a service to their country and their public duties. So while people think these two men are shrinking their responsibilities, they think they're serving the public.