it’s partially because we are running out of options that have the headphone jack, and the only reason to remove them is to boost sales of more expensive bluetooth sets. Bluetooth really doesn’t reign supreme yet because wired headphones are still more convenient, cheaper to produce, and last longer than their bluetooth counterparts. the only reason it’s so common is because it keeps getting removed from phones so people don’t have a choice in the matter.
that isn’t the typical experience though, and letting your batteries drain completely is bad for them. also if you don’t have some sort of routine, a lot of people (myself included) end up forgetting to charge them and end up with no working headphones until they can charge them again, which is pretty annoying.