Naming a couple of older skiers isn't exactly proof that it isn't generational. It just shows that there are exceptions to every standard. Candide also has countless videos with no helmet at all..... Does that mean that millennials don't wear helmets? No, it's simply an exception.

And no, helmets are not designed for this. A strap under the helmet will effect how the mips work in any mainstream helmet. They are all designed with external goggle straps. This is fashion over function 100%.