First of all, the design is laughably ugly.. it just looks really weird and you can tell Apple is trying to make it look like an Apple MacBook or Mac PC (probably they did it on purpose so that it matches with someone's MacBook Pro laptop). The headphones look pretty bulky which defeats the purpose of portability. On top of that, Apple already has to compete with themselves.. they already own Beats headphones which look way nicer and people would rather get the better looking headphones rather than the ugly ones. The aluminum metal they use isn't anything special, Bose often use aluminum too and they don't cost that much.

I think the biggest reason why it failed is the price.. it's a whopping $549, Apple is getting way too arrogant and think they're on top of the world. In tough times like this, expensive headphones are not what people are likely to buy. You can buy some Sony or Audio Technica wired studio headphones and get a converter attachment which turns it into a bluetooth headphone.. and it'll sound better, look better, and cost way less.

Wired studio headphones converted to Bluetooth using an adapter:

You can also just get a Bluetooth adapter converter too which works for all wired headphones:

Be smart and save money.

If you want good noise cancellation and good build quality, get a Bose headphone (which you can also convert the wired headphones into bluetooth using an adapter).

So what could Apple have done? Maybe they could have made the headphones better looking, make it more portable, make it lighter, add an option to connect a 3.5mm headphone wire, add a built in offline fitness tracker (pedometer, heart rate & calories tracker, offline voice assistant coach, etc.) with local storage for offline music when working out (like Samsung's headphones), add an option to turn the headphones into a bluetooth loud speaker so it doubles as a headphone and bluetooth speaker, make it water-resistant so sweat doesn't damage the headphones, lower the price, etc... Who knows, maybe people will end up buying the AirPods Max once the price is lower, maybe that's all that's needed.

Apple is getting rid of the charging port in 2021 as rumored, so you better enjoy wired headphones while you can on the iPhone because it'll be the last time you can plug in any headphones through the lightning port.. this is all a cash grab by Apple, don't think Steve Jobs would approve of that.