With respect to Bob, I do somewhat disagree with the premise. Many IP's that get the "mature" reboot (and don't horribly flop) usually need it because the orignal, lighter tone just makes the property feel out of place. In some cases, the darker tone feels more approperiate for some properties. Let's look at the titles that Bob looked at:
Pokemon: This is a game that, for the most part, based on a game mechanic and a copy-paste story line. Sure, they could make a dark, mob-buster plotline, but it wouldn't work (you are 13-18 year-old "trainer" after all). It never really takes itself seriously in the story department because the bubbly atmosphere of the game is part of the game. I even saw the first screen-shots of the new game, and it is virtually unrecognisable in it's new style.
Batman: This IP is, at its heart, an organized crime/detective story, and less about Batman running around in his tights battling a clown (Joker is a violent killer, after all). A darker asthetic simply makes more sense with the material content. Even the cartoons had a darker theme to it. I think after the timeline that started with "Batman: the Animated Series" and ended with "Batman Beyond," the series lost something when it decidedly went for a less-darker asthetic. They barely even mention death, even though the concept is an integral part of the origin of Batman.
Superman: The slow death of Superman in the media has only been amplified by the sudden realization that he is wholely unrepresentatitve of modern times. His near-complete invinsibility and warm feeling worked well in the risiing US of the 1930s and '40s, when sheer might was the way to fight evil (ala the Axis powers). In the '50s and '60s, the American economic Zenith made Superman's might similarly representative of the power of the American economy. But after Vietnam, the turmoil of the late-'60s, '70s and '80s, Oklahoma City, 9/11, Katrina, and the economic collapse, his invincibility feels less hopeful and more the rose-colored memories of days-gone-by. Smallville tried to reboot the franchise, but it is almost unrecognisible as Superman as we (used) to know him.
The Bionic Commando reboot and Street Fighter movie: utter failures because they missed the point of the series' to begin with (platforming and cartoonish fighting, respectively).
Battlestar Gallactica: The "hopeful future" Sci-fi series died with Enterprise. As we move farther in history, we're realizing that the faults in humanity, the basis of many of the species in the first Star Trek series, likely aren't going to be resolved as nicely as we hoped. That's why series like the new BSG and Firefly have become the next wave of mid-far future sci-fi series.
Mario: The franchise was built in the '80s, when the idea of a plumber saving a princess from a oversized turtle was a story line that people would accept. It has rarely strayed beyond the self-realization that that completely absurd story could never be tken seriously (ever more confirmed by the Mario Brothers Movie, which we all agree never existed). So they rolled with it, and stuck with the lighthearted (and, especially in the RPGs, self-flagelating) notion that it was an absurd concept that eventually has become the joke of the series itself. Mario has done the near-impossible and used the combination of nostalgia and broad appeal to maintain a steady and constantly growing following, minus a few trip-ups (Sunshine).
Point is, some things do need to grow up as we loose that innocence of childhood. Batman, Battlestar, and others were fun at the time, but they now feel alien in our world. Hanna-Barbara cartoons feel dated, almost like walking into an elderly person's house. Others, like Mario, Pokemon, and Street don't need to change because we remember those things for different reasons. We'll always look back on those days with rose-tinted glasses, but there is a point where we all sit down and try to watch/play some of those things and feel completely out of place. I don't remember my childhood through Desert Storm or the '92 recession, but now I know they existed while I watched the Sonic Cartoon series and played Super Mario Land on my first grey-brick Game Boy. Don't let that nostalgia deny the maturing of a series.