My own sense of style went to pieces in my 40s, for various reasons, but I hope it's returning to me now. I agree with her that essentially there's no need to change how you dress as you get older if you've figured out a style which works for you. As long as you simplify things and don't show too much flesh (which you shouldn't in the Australian climate anyway).
Yesterday I was discussing age and ageing with a colleague who is in his 40s and when I said I was 51, he replied, "Well, at least you're still riding your bike". It was meant - and received - as a compliment but later I thought to myself that this is part of the problem that confronts you as you get older (and I'm pretty sure that wouldn't have been said to a 51 year old man): there is an unspoken sense that everything is going to fall apart and it's slightly incredible that anyone over 50 still manages to have ideas and move around in the world.
My father started wearing jeans in his 70s. Co-parent's mother wears jeans at 87. Most of the clothes templates for older people which I carry in my mind don't accomodate that image - because there are a lot of oldies who still dress in 'old codger' or 'dress and handbag' style. But they probably always did.