I have pretty much the same conclusions as you draw, except I feel I do need my power meter. It really does help me ride better, in the ways you point out and more. Anything that makes a significant dent in my ability to ride better is something I need.
That said, I don't require it. I'd screw up not knowing my power and overdo/underdo something. But I would still have a great ride.
Maybe in a couple years I will have enough sense that I won't need the meter, but I find that in certain conditions I can still be pretty far off in my guesses of how much power I am burning. Topping out on a hill I am usually at less power than I think I am, and on really hot days I can sometimes be doing 1.5x my FTP and feeling like I'm at my FTP.