I can't agree with Bob on this one.
In my opinion, while not every reboot needs to be 'gritty', that doesn't mean making a gritty reboot is a bad idea. The fact that many reboots are gritty doesn't change that at all. And of course, it has to fit the source material - if they ever make a live action Strawberry Shortcake movie, it shouldn't be 'gritted up'. But in some franchise's case, it really is the only way to go.
Batman is probably the best example.
Even if you look into the comic, Batman simply isn't a very cheerful figure at his core. He's a kid who saw his parents murdered in cold blood. He represent vengeance and justice. He's a vigilante. He uses fear and many underhanded tactics that are usually privy to bad guys, to get results. Heck, if you go far back enough, Batman even used guns in those early comic books.
Characters like Robin have been introduced to make Batman more likeable and more 'humane', both from a marketing and characterization point of view. No matter how many zany adventures he's been through and how many Saturday morning cartoon he shows up in, nothing will change the fact that Batman is a guy's who's extremely traumatic childhood has driven him to dress up in a costume and beat criminal up.
Now you take Batman to the movies, and you have the so far awesome 'Nolan-verse' movies, which are pretty much has dark and gritty as it gets. But here's the thing - if you look at the first cycle of movies...
The first two had Micheal Keaton and Tim Burton. And while I personally don't think they aged very well, those movies were dark. Gotham city was spooky, creepy, gothic. The bad guys were violent and evil. Batman was one of the first PG-13 movie I saw and it gave me nightmare

, and I know I'm not the only one. Devito's penguin in the second one was horrific as well. You can say what you want about those movies, but they weren't exactly kid movies - even thought they were about a character marketed to kids.
And then come the Batman Forever. The silliness is cranked up to 11, and so are the colors. Robin is introduced. The bad guys are much more 'colorful' (Gone is the sleeky purple of the joker or the black & white of the penguin and catwoman... instead we get practically glow in the dark Riddlers and one of the worse looking Two Face ever) and are more crazy funny than crazy scary.
And then there's Batman & Robins, which goes even more over the top in both color, zaniness and wackiness... and at this point, the bad guys aren't scary anymore. More importantly,
Batman isn't scary anymore. He stops being this man filled with pathos who's pain and hurt have turned him into a vigilante and becomes a bored millionaire dressed in a costume.
I know there's more wrong with the last 2 movies than just the tones and the theme... but it's a huge part of it. When my younger self walked out of Batman Forever, my first reaction was 'Where did the grittyness go?' - it is in my opinion a huge part of why those movies are now looked at with disdain. Yet... if we go with your arguments here Bob, those movies should have in fact been better or at least, in a better direction than the rather gothic Batman and Batman Return.
To go full circle with Thor... yes, he's a magic space viking with a hammer. But even the Marvel comic draws pretty heavily on the 'real world' Norse mythology - which are not a happy place. Odin is the gallow god after all. None of the norse gods are nice guys and most of them have plenty of angst and drama in their background. While a Thor movies doesn't need to be gritty to be good since the source material isn't very gritty at all to begin with(And I'm looking forward to seeing it!) - there's definitely room for somebody to think it could be gritty since not everyone is familiar with Thor the Marvel character (whose is a rather obscure hero compared to Superman or Spider-man), while I would think quite a few more people have at least a passing idea who Thor the Norse god of Thunder and War is.
If the movie were about the 'real world' Norse gods coming to 2011 Earth instead of the comic book norse gods, it certainly would be a lot grittier and meaner after all. I mean Thor is the god of war (among other things) of a people that was known for martial prowess, sailing, raiding, pillaging and raping (I know that's not all they did, I'm just talking about reputation here). Geez... could it be a gritty and violent movie? What do you think? And not every critic (or movie goer) is a comic book fan or not all that much about the Thor character in the first place. So no, it doesn't come as a surprise that people are surprised that the movie is kid friendly.
