The Star Wars prequels were really something else. In the third installment (Revenge of the Sith), main characters died all over the place and then children were murdered. Children - were - murdered. So, do you remember many people (if anyone) reeling back in the theater and screeching? Getting sick? Covering their eyes? Why did it seem to have no large impact what so ever? Realistically, such a horrid thing should have been like this:
http://www.youtube.com/watch?v=n-cHXkGchEo

It wasn't though.
Star Wars is just as fantastical a setting as Game of Thrones, so why in the world did the Red Wedding have the effect it did and Star Wars completely failed in showing almost equally disturbing images? Is it because it was more sudden and 'out of left field'? Is it because Game of Thrones uses less CGI? Is it because they showed more gore? Or is it because a mythical/fantasy setting full of ice zombies and dragons is somehow more believable then a sci-fi setting full of space wizards? Both Game of Thrones and Star Wars take place in equally bizarre and silly environments, so what is really going on here? Well, our minds are smarter then you might give them credit for. We know fantasy worlds aren't "real", but we also know how reality is basically supposed to work. It doesn't matter if the story we're watching is taking place in the mystical land of Westeros or on planet Tatooine; that's not what makes something real to us.
What makes something real to us is an effort to convince us it is, that's 'suspension of disbelief'. How does that happen if our minds are so good at identifying fake things? Well, believe it or not our minds might not be looking exactly where you think they are when judging this stuff. It's not looking at the dragons or sarlacc pits, it's looking at things it can identify; things it already knows the workings of. Take people for example: when you see people landing fine from 50ft drops and walking away unhurt, that's a subconscious signal to your brain that everything you're seeing is most definitely fake. When you see someone actually brake a foot from a small drop or suffer another serious injury that any person would had gotten from the same situation, that's a signal to your brain that what your seeing is real, even if it isn't. It doesn't even matter if there are dragons or spaceships flying around, it never did.

That is one of the things Game of Thrones is quite good at: emphasizing mortality. The Red Wedding in particular did this well, so well that many people forgot they were watching a TV show. You know what else added to the wince factor of the Red Wedding and made it seem so alarming? Aside from the great acting and realistic reactions from everyone, it was one of those things that was so horrific, it could be true. That's the shitty thing about reality; it's shitty. Our own history is full of this kind of stuff, and we know that. We know how crappy people can be, and we know how pointlessly grim and sudden death can be to. What we don't know is how destroying an entire world full of millions cannot elicit a single tear from the only survivor who had to watch, (a survivor who seems to suffer no real emotional trauma later). Millions died, but it wasn't that big of a deal. Plot wise it most certainly was... but for us, personally? No, it wasn't really that big of a deal at all. No one actually cried over Alderaan... but they could have. All it would have taken is a little convincing that this was as big a tragedy as the plot was trying to convince us it was. Again, our minds weren't looking at the space death ray, they were looking at the people, most notably the person watching their planet explode. That said, I've seen people act more hysterical to their dog getting hit by a car then how princess Leia acted to seeing her planet get destroyed.

If Leia actually had a believable, gut-wrenching breakdown, some people might have been better able to understand the gravity of what was supposed to be taking place. Sensitive people might have even freaked out, to. That's how far a situation can pull you in if it seems believable enough. The reason why the Red Wedding (and Game of Thrones in general) can make people feel uncomfortable the way it does is because some part of people's brains believe what it is they're seeing. Whether or not you love or hate Game of Thrones, you have to applaud this fantasy world for being so believable it can do that to people. Most shows about modern day real life can't even do that.

But don't get me wrong here, I'm well aware that's not the purpose of Star Wars. Star Wars is literally just there to entertain and have fun. It is just fine the way it is. Funny enough, things like Alderaan exploding and other disturbing scenes in Star Wars were probably under-acted and done the way they were on purpose because of the unsettling implicates. That just goes to show there is place for everything, Red Weddings and cartoonish space battles alike.

The reason I brought all this up to begin with is because I think it's important to realize and consider these things and the different effects they have on people, especially with the internet being so full of creative minds. I know it's easy to say "This is all fantasy, so whatever" but that's not really true at all. Regardless of what it is you're making, everything is just as real as you decide to make it. And just like with the Red Wedding, take that concept as positively or negatively as you want, because it can easily be either depending on who you ask.