how they “look noticeably better”
Mostly shape. A well shaped hat vs. a cheap one makes the entire face look better.
When did style become more I important than substance?
They want both. Didn’t you buy a “new” (albeit relatively affordable) shaitel for your son’s chasunah? I’m sure there were other wardrobe/makeup/jewelry expenses as well, for you and others in your family as well. Wasn’t the “substance” the simcha, not appearance? The answer is that we care about both. Caring about one’s appearance doesn’t mean the person is shallow and lacking substance (although to an extreme, it does, a Borsalino is not extreme).