This is just a salty statement and you're a much better poster than that. I dont know about the shadowboxing thing, whoever backed that notion is an imbecile.
That said, boxing has existed in very high quality LONG before mitts became a big deal. Saying they're not absolutely necessary is not controversial. Its rooted in fact.
About going 100% power. An odd thing, I noticed recently that the less time my students spent doing things as hard as possible the quicker their bodies learn how to do them at all. It's incredibly difficult to force form and when you fully mash the gas pedal down, some form WILL be sacrificed. I'm still experimenting, but it's looking like the more time they spend relaxed with an emphasis on holding positions and changing them, the tighter they remain when they do go to maximum exertion.