My parents freaked out quite a bit about the "magic" in video games. I wasn't allowed to play Diablo 2 at all because of the magic and such, besides the fact that you could play as a holy warrior who was trying to destroy the lord of destruction. They weren't that worried about violent video games though.
Now, with my own kids (11 and 12) I pretty much let them play any T game they want. When it comes to M games though, I have to review the content first before I'll let them. My wife and I are both gamers and we're of the same mind in it. Personally, I don't really like the mindless killing for the hell of it kind of games and prefer if there's violence for it to be more of a survival situation, such as Fallout 3 or Borderlands. Murder for the sake of murder just doesn't sit well with me (GTA or Carmageddon series comes to mind)
Now, when sex comes into play, that's a different story, mostly because they aren't even in their teenage years yet. I see it this way, when I was young, I went hunting with my dad, I helped him clean the animals we shot and violence was just a necessity. The blood and gore from the animals was necessary for us to eat them. Same thing when it came to war games such as Medal of Honor, it was out of necessity really. The killing of the enemy because they were going to kill you.
When it comes to most gameplay though, the sex, nudity and promiscuity don't really add anything to the story and are tossed in to be "edgy". It's one thing to have it be part of the story and do a pan-up or a fade out from a scene between two people in an RPG that have fallen in love blah blah blah, it's quite another thing to have strippers trouncing around with their pasties or the like.
Especially considering I'm trying to teach my boys to not go after anything and everything that has two legs because it will only lead to emotional, mental and physical hurt for them and the other person, especially if it's before they're ready. I don't villify sex, but at the same time it really should be one of the furthest things from their mind at the moment. I talk quite openly about it with them since I know they're getting an immense amount of misinformation at school from their friends and the like. I don't want them getting some naive idea of sex and that it's just another bodily function like a sneeze. My kids will never be one of the ones to jump in on a homecoming gang-rape. They'll respect themselves and women too much to even consider it.
I'm trying to teach them that by screwing up and having a kid before their ready, or catching an STD for 5 minutes of "fun" will severely put a damper on their life. I will never be high-fiving them for "nailing some girl" and I will always try to reinforce in them the idea that they need to wait until their ready, not until their hormones say they are. I have enough problems trying to fight this mentality with all the crap that's on TV and all the bull that's being fed to them from their peers from parents who care so little about their own kids that they expose them to so much crap that they already have little to no respect for themselves or the opposite sex. So yeah, I have a problem with sex in games when it comes to my kids.
Oh, and concerning the whole "magic" aspect, pffft. They aren't going to start waving a wand trying to cast magic missile, since that's just not possible. There's a difference between fantasy and real life. I've always explained that to my kids. They know the difference for the most part and the moment that line begins to blur (such as when I found out my youngest had seen the movie Child's Play before they were with me and was having nightmares) then it's removed from them until they're mature enough to handle it, which is why he's not allowed to watch horror movies.