It's probably because the aesthetic here is relatively bland, and sandals are an existing form-factor of shoe. Airpods are aggressively sleek and white, and they sit in a weird uncanny valley of accessory and tool. Technically, wired earbuds have the same hanging-stem, but everyone's used to them, so no one notices them.

As to the aesthetics, I'm sure people thought the same of all types of bicycles. Penny-farthings used to be the cultural norm, and people still ride less-common forms like small-wheel and recumbent bicycles.