That is totally fine if its end up on ebay. Thats exactly my point and you asserting the same. If it ends up on ebay means i didnt use it, means i didn't need it. Someone on ebay will purchase that coupon and will buy that charger if he/she requires it. Again, it asserts my point, charger for someone who needs it.
As for thinking like businessman, yes, they can inlcude the the price for that coupon in the price of the phone, just like as usual they would provide us with the charger, but now instead of charger just provide the coupon. Its just an option. Price is already paid by the customer.