I have a theory that for many people their enjoyment of music is largely driven by associations they have built around the music. Through these associations music becomes a part of your identity, taste in music winds up being used as shorthand for that identity and enthusing about that taste with friends serves as a way to reinforce your sense of self.
If you haven't built a song into your identity in that way then your probably not going to get why someone who has loves that song as much as they do. A good games related example of this is the Mario theme song. I love that song to bits because a) it's good and b) it's associated with a lot of positive memories. That song isn't going to have the same impact on a person who has never played a Mario as it does on me.
Like my love of the Mario theme, your appreciation for theme music probably has a bit to do with your enjoyment of anime and videogames. I would assume you have lots of positive memories associated the soundtrack of a game your like or the theme song to a good anime. Those memories enhance your enjoyment of the music and make you more likely to enjoy similar music.
I would totally recommend exploring music a bit more though. You seem to like a pretty diverse array of bands, why not explore rock or rap or psych rock or whatever genre Gorillaz are? The internet makes doing that super easy and it can be quite fun. Getting into music can be as easy as finding a blog you like and following it until you start developing your own tastes (I didn't like music all the way through high school because I thought the stuff my friends liked sounded terrible. So I'm speaking from experience here).
Also you might like Symphonic Metal. Personally I don't care for it, but I have noticed that a couple of my friends that really like videogame music or anime theme songs tend to like it. Stuff like Nightwish does tend to remind me of anime themes and some of the other stuff wouldn't sound out of place in Castlevania or a JRPG.
If you like it it could serve as a gateway into the wonderful world of metal, which is a shockingly diverse genre of music (As an example of that, I got into metal because of the similarities between Drone Metal and Ambient Drone. I then worked my way towards normalcy by getting into Doom, then Black Metal and then eventually all the way back to old school stuff like Dio. All of those sub-genres are quite different and I've really only scratched the surface of the genre).
If you haven't built a song into your identity in that way then your probably not going to get why someone who has loves that song as much as they do. A good games related example of this is the Mario theme song. I love that song to bits because a) it's good and b) it's associated with a lot of positive memories. That song isn't going to have the same impact on a person who has never played a Mario as it does on me.
Like my love of the Mario theme, your appreciation for theme music probably has a bit to do with your enjoyment of anime and videogames. I would assume you have lots of positive memories associated the soundtrack of a game your like or the theme song to a good anime. Those memories enhance your enjoyment of the music and make you more likely to enjoy similar music.
I would totally recommend exploring music a bit more though. You seem to like a pretty diverse array of bands, why not explore rock or rap or psych rock or whatever genre Gorillaz are? The internet makes doing that super easy and it can be quite fun. Getting into music can be as easy as finding a blog you like and following it until you start developing your own tastes (I didn't like music all the way through high school because I thought the stuff my friends liked sounded terrible. So I'm speaking from experience here).
Also you might like Symphonic Metal. Personally I don't care for it, but I have noticed that a couple of my friends that really like videogame music or anime theme songs tend to like it. Stuff like Nightwish does tend to remind me of anime themes and some of the other stuff wouldn't sound out of place in Castlevania or a JRPG.
If you like it it could serve as a gateway into the wonderful world of metal, which is a shockingly diverse genre of music (As an example of that, I got into metal because of the similarities between Drone Metal and Ambient Drone. I then worked my way towards normalcy by getting into Doom, then Black Metal and then eventually all the way back to old school stuff like Dio. All of those sub-genres are quite different and I've really only scratched the surface of the genre).