Honestly I don't mind the lack of a charger at all--the high-power USB-C charger in the 11 was nice and I actually use it once it a while, but let's face it, USB charge ports are everywhere now.
Leaving aside the 5 USB bricks sitting in a drawer, and the one high-power USB-C brick that came with my 11 that's plugged in, and the USB-C brick that my MBP is plugged into, and all the ports on computers... I still have 4 charge ports on wall outlets, 2 in the car, 1 on my home theater system, and 4 ports on my couch.
Sure, it's silly, but in an era where you can literally buy a couch with USB ports, you can legitimately get away without putting another charger in the box of umpteen million phones for the sake of the small number of people who don't have one. We've basically reached the point where a USB charge port is the equivalent of a wall outlet--it's just a thing you can assume people have, and if they don't they'll have to buy some to participate in the modern world.
The headphones are a bit more of an issue (and less of an environmental one), but unlike the charger you certainly don't need them to use the device.
I guess in the grand scheme of things I look at it like this: Apple sells something like 175-200 million iPhones a year. 98% of the people who buy those already have chargers around. The handful who don't can certainly afford to buy either a nice one for $15-20 or a cheap 4-pack for like $12 if they can afford to buy a $600-1100 phone. And Apple saves roughly 100-150 million unnecessary chargers from being built and promptly tossed into drawers, which is a nontrivial ecological benefit. I'm less able to speculate on the ratio for headphones, but it's probably still in the tens of millions at least--certainly the last several pairs of mine have gone right into a drawer without even unwrapping them.
All that said, "Well, there's so much in the phones already." is a garbage way to try and introduce this from a sales standpoint. You don't try to couch it in terms of value, you say right off--even if it's a lie--that you don't want to put tens of millions of chargers and headphones in drawers when people already have a bunch of both laying around, so you're doing it for ecological reasons.
If I'd been pricing them, I might have even bumped the list price down by like $10 or something--call it $989 instead of $999--to try and sell that it's an ecological decision rather than a nickel-and-dime one.