I honestly, never really put any extra energy into caring for my battery, it just seems to be fine. When I see it gets low, I just have the reaction to throw it on a charger, and leave it plugged in for a bit, then I'm good for a while. Wired are good backups, yes, but I don't think in this day and age, they are the perfect solution, just the same that wireless are not either. But for my runs to the grocery store, the gym, or going for a hike. I'd rather not have a cable constantly getting in my way, and being able to freely hold and move my phone around with no issue. Of course that would be my use case, possibly making it subjective, but I imagine a lot of common users are pretty much about the same.

On the "needing to have another pair of headphones", I mean why not? I don't know how many wired earbuds, over the ears, and such I had growing up. They weren't high end, or even mid-tier quality, but you could find them pretty easily. Just as easily as you can find them now. Not saying "take two different sets of headphones" with you whenever you go on a trip. That's dumb, you'd have a higher chance of losing something that way. Just take the wired ones, with an adapter because that makes sense for a long trip where you want to conserve battery life and you're just sitting in a car anyway. Also those adapters are pretty tight fitting, I leave mine just stuck to the headphone cable.

I'd also think if you cared about your audio equipment that much, you would probably be probably be able to keep track of a little adapter pretty easily.