Ultimately, however, brining has outright phenomenal effects on meat tenderness and moisture that simple cannot be replicated by timing and temperature changes. It creates complex chemical changes in the muscle that lead to a far simpler cooking process, and the meat also stays moister longer than cooking. This is covered in detail in cooking chemistry books.
See, for example: http://modernistcuisine.com/recipes/injection-brining/
"Yet the perfect roast chicken is nearly impossible to achieve in practice. The temperature required to brown and crisp the skin is so high that it leaves the meat underneath scorched and dry. The dark thigh and leg meat similarly need higher heat than is ideal for the white breast meat. Brining the chicken in salt water can help the delicate breast meat retain more juice at higher temperatures, but the brine has the same effect on the skin, which then ends up unpleasantly chewy."
This is basically scientific fact: you cannot achieve what you want without brining without putting in effort and time.
It's not trivial, but I think it's pretty easy after you've done it a couple of times.
> Techniques like spatchcocking make this easier, but it all trades off time and convenience.
Right. I do something similar, though I cut the legs all the way off. It takes a couple of minutes, but it's pretty simple.
For what it's worth, there are a number of simple recipes for roasting chicken that don't require brining or any long marinating period but still come out nice and moist.
Even a basic roast will be fine as long as you don't overcook it.