The problem is, you have to think logically and understand that the new USB-C MacBooks are a "niche" product, compared to the expected audience that these are aimed to attract. Adding a USB-C cable to the package would really just create a ton of e-waste (which doesn't fit with Apple's philosophy) as you figure less than 5% of people who buy these would actually be able to use said cable and likely less than 1% of those would actually USE the cable to charge from their Mac. They are designed to have multiple days worth of battery life from a single charge of the case alone. You shouldn't really have a problem getting through a day with plenty of battery life to spare. Just plug it in at night. If the battery case was non existent and the AirPods needed to be charged after 5 hours, I can see the argument. With the charging case implementation, it is a non issue.