Plenty of older women models around. They are almost as essential to ads and magazine articles as models from other ethnic groups.
When it comes to size and shape, garment companies want to show their clothes off to best advantage and in a way that makes it easy to see the main features. There are standard sizes clothes are cut to fit and it makes sense to display them on models of the right proportions.
The problem is real people come in so many different sizes and shapes manufacturers would have to make clothes in hundreds of different sizes, all in short runs. This would mean that the cost of clothes would rocket up.
Surely all of us, as we reach adulthood know the vagaries of our shape and size and we filter out all clothes that we know in advance are unflattering.
I have no waist, my hips are almost level with the bottom of my rib cage, so I try to avoid wearing clothes that fit to the waist. They make me look huge, even though I am not over weight. I know what colours suit me and what styles I like wearing. So if I see a model in a coat with a tie belt in a fetching shade of black, my eye moves on, the style and colour will look awful on me, so my eye moves on.
I am quite happy to see clothes on a slim model. It makes it easy to see the garments features. I rarely look at their faces, so do not notice how old they are. It is the clothes I am looking at.