I think Catherine do not like having too much hairspray in her hair. To do a updo even a simple bun, lots of hairspray needs to be used. For her ponytail the other day, she did not use lots of hairspray and towards the end of her visit, some hairs are running loose on top of her head. Anyway, I think she looks good with her long hair, an updo, even the ponytail aged her.
I think this calling for hair-up is getting too much, every single appearance I saw people complaining about her hair. It's the same as Queen Max case. Max always change her hairdos and did hair-up marvelously on frequent basis. But whenever she appear with hair down, people are complaining why no hair-up and commenting how badly damage her hair are. But royals also needs to let their hair rest too in between hairdo. So for this case, should she continue to do a hair up for every appearance with tons of hairspray or let her hair rest to recover a bit?
You and I are in agreement on this. Catherine is fortunate enough to have a luxuriant head of hair which complements her face. And I do think that the pulled-back or-up look makes her look older. She's still young enough to sport a look like this, and that is part of her identity. Time enough to wear it in an up-do in the decades to come. Most women would kill for hair like hers!