Indeed, that doesn't add up.
As I said, it's all very subjective.
If I have an iPad to be able to listen to music and watch movies on it, it's obvious that I consider earphones to be
needed.
I can use an iPod (touch) to surf the web, game and access my cloud without even thinking of listening to music (indeed, that's what I do). I can, too, use my phone without any headset. Most of those who need them have their own quality ones, instead of those horrible Apple's ones.
A charger, obviously, is of primary importance, as without it my product would cease to function.

Earphones are accessories, so that's really off topic.
What you state about cables is off topic too, as external accessories using I/O are expected to come with their own cables.
I have never touched my iPod/iPhone earphones. I'd need other accessories, such as a decent case, for example.
If Apple added those earphones to the iPad package, I'm sure you'd totally agree with that, coming up with a poor supported argument, again. But that's just my impression.