What a storm in a teacup is raising here. Some people bad-mouthing a CP couple and CP Mary in particular for doing a good job representing their country abroad without any self-interest, politically or financially, and promoting their country's export?{edited for consistency- Empress}, and I don't get this negative attitude at all.
Following the same strange logic in asking for concrete results of these visits, one could abolish any state visit by every Head of State, President or King, as well. I haven't heard much about explosive immediate 'results' in this case either. For example, why should the German President pay a state visit to the Netherlands next month? Relations between the two countries are very good these days, no new wheels & deals will be set in motion during that visit, so Queen Bea should leave her tiara in the vault, the President should stay at home, goodwill is a highly unnecessary thing, on top of it it costs the taxpayers money... let's call it off already!
Royal representatives being above self-serving political and economical interests make them ideal ambassadors of their country. Visits like this one are not about creating a mass media hype or taking over another country or city by storm but about visibility, appearances, doing their bit for charity if it fits the agenda, leaving a personal impact on the representatives the Royals meet and about creating & adding to a positive image of their country both in the place they visit and for their own people at home. What's so bad about that, may I ask???