I think the topic has already been widely discussed in other threads on other occasions. I personally would like to see them more often at such events, interacting with their peers, because I believe it's important to build long term friendships or alliances, eg Letizia with Maxima as they are both spanish native speakers. But let's not forget that the King & Queen are still very active and most times visit such events themselves, with Felipe (& Letizia) staying in Spain (I recall it's a tradition that JC & Felipe do not leave the country at the same time, pls correct me if I am wrong).
IMO F & L have done well so far, Letizia always looked gorgeous at the few events they have attended in the past, truly a handsome couple