I mourn the concept more than the content. There is a remembered innocence here, indicative of all the things we lose as we grow older, as we're forced to learn to accept adult responsibilities, like making our own cereal and not sitting directly in front of the TV.
As for the shows, I don't miss them. And I'm one of the lucky adults who still manages to get as excited for things I like now, as I did for things I liked when I was a kid. They just aren't the same things. But if He-Man could replace naked boobs, the world would be a strange and terrifying place.
(And Fisto would be a very different character, as would Ram-Man and Mat-at-Arms and Beast Man and Lockjaw.)
In truth, I shouldn't even side with those in mourning. I was never as big a fan as others. In my later adolescence, I would often sleep in rather than get up to watch cartoons. And I stopped eating cereal at a very young age, preferring coffee and freshly hunted bison. Though I still took my Flintstones chewables for a while. You need vitamins to kill bison.
It's funny, actually, because when I first read this question, I read it as Saturday morning bison, so regular were my hunting trips to kill large game with my bare hands. Coming of age is an arduous task for one as manly as myself, and the rites of passage are near deadly. Though none, I must admit, were as stressful as getting my license. That's a tough one for everyone, even people who've never run down a ton of galloping meat and choked it out with their rippling forearms.
Short Answer: This shit went off the rails.