Could be part mindhack! I remember Apple's iPod advertising campaign which centered around silhouettes of hip looking users with the trademark white dangly wires snaking into their pocket. I guess with this desirable tech hidden in your pocket, the wires were the best way to recognize that someone had one!
I guess since airpods are visible (and expensive) they are now the desirable focus, and anyone with wired earbuds is hopelessly out of date!
Making them stick out visibly from the sides of people's heads was absolutely a design choice so that people could be "seen" with the product.
Apple is very big on being a status symbol which is why they put a giant shiny (at one point glowing) logo on their laptops and why they spent a lot of money trying to convince iphone users to not use a case which would hide the logo.
I guess since airpods are visible (and expensive) they are now the desirable focus, and anyone with wired earbuds is hopelessly out of date!