>but I imagine that I would just leave the adapter on them 24/7?

Except people often use same headphone with both - phone and pc, so you will have to remove the adapter anyway.

Thats one of the most fatal flaws. Apples proprietary plugs aren't even standard across their own devices.

I'd rather keep the 1/8" to 1/4" adapter on it. Lightning or USB C means now I have two adapters to carry around.

It shouldn't be required either way, but I've occasionally zip-tied two adapters together so I can swap between them quickly.

I think it might be slightly annoying to have a two-inch-long dongle hanging off your phone at all times, particularly on a brand of phone that's specifically marketed (and purchased) for being sleek and clean-lined.

Correct. It really isn't a big deal.

Until you want to charge and listen to music at the same time, which I wanted to do on a flight recently. I had to charge up to what I thought was enough and then put the headphones in. Annoying.

My wife also brought Lightning headphones, which didn't work with anything except her phone, leading to her using the cheap airline ear buds for the in flight entertainment system.

Alternatively you can pick up a dual-port adapter and charge while you listen:

For example, https://www.amazon.com/dp/B00E5AHZYA

I take it you only use one set of headphones and that you only ever connect them to the phone?