I'm afraid he's a little out of the infantile Dark Lord stage. We may be into skulking and temperamental early adolescence, a phase of Dark development I know well from my time with you. Unfortunately he has no friend to spend that troubled time with, and I have stretched this hapless metaphor to its snapping point.
As for the choice you mention—it weighs on me heavily, yes. My Pensieve has been invaluable. And—at times my heart proves difficult to untangle as well.
One can think almost endlessly on that question, that of Muggles. Though they've answered some of your wonders themselves—the further you look into Muggle artistic criticism, the more you realize that there are valid criteria for judging creative output beyond its practical-magical usefulness. I'm enclosing a text that's been particularly helpful with that, if also dry. One thing I've found particularly difficult to realize, as a wizard, that to a Muggle a life of the mind does, in fact, entail losing any ability to affect reality directly. Yet, for that, it is often surprising how many of them choose such a life, and those who don't, who choose professions of battle and labor where they can change physical reality through their own natural means, are generally considered to be a second class. I'd heard it proposed that they're unconsciously mimicking wizarding society. I think perhaps the cause and effect there is off.