Some people don't want to spend extra money when they already have working headphones? The new iPad got rid of the headphone jack. Why? It's an iPad. You can't use the excuse some manufacturers use with phones, which is that there wasn't enough space, because it's a large tablet. And considering lots of musicians use iPads for GarageBand, taking away the headphone jack could be a dealbreaker for them.
There is no point pushing ideas like this, companies like Apple most likely only did this so they could boost AirPod sales. If you're getting rid of the headphone jack to make room for something new and actually useful then I'd understand, but the new S10 still manages to make room for one, even with the huge battery and in-display fingerprint reader, which is what the maker of my phone, OnePlus, used as an excuse when they ditched the headphone jack on the OnePlus 6t - they said it was for a bigger battery and that fingerprint reader.