Have you ever tried to process RAW pictures (including pictures from Hasselblad and Fuji medium format cameras, or Canon and Sony full frame cameras) and/or edit 4K 60p video on a MacBook? Well, me neither, because it's simply impossible. Surprisingly enough, that's what I do on a regular basis on an iPad Pro. The power of the ARM setup on that machine is unbelievable. So, there you go, that's single-handedly a reason why this kind of computer makes more sense to Apple (and to me) than an underpowered Intel MacBook. I do agree that the keyboard and trackpad setup is bullshit though, as it won't really improve the apps I use for what I mentioned above--they're built for touch, not for a mouse pointer.

As always, it's a matter of what's your purpose. As a developer you'll be much better off with a MacBook Air, for that measure, which I think is a much better piece of hardware than the 12" MacBook.