THIS IS MY OPINION AND MY OPINION ONLY! YOUR OPINIONS ON THIS MATTER MAY DIFFER FROM MINE. THIS MAY NOT MAKE SENSE AT ALL TO YOU AND THAT’S FINE. PEOPLE ARE ENTITLED TO THEIR OWN OPINIONS.
Normally, Anime are either original ideas animation studios though of or adaptation of other media notably Manga or Light Novel. For these animations which are adaptations from other media, some people find it irritated by the fact that they know what’s going to happen next in the anime. Some people I personally know will not read the original source even after they find out that there are Manga or Light Novels for it. I understand why these people prefer watch Anime and not read the original source at the same time, however, I do not have any problem with doing so and will read the original source even if the story of original source has gone past the story in Anime.
To me, it’s not just anime but all other medium of entertainments (movies, books, games, etc.) are enjoyable even after I know the plot and the story. That’s why I have no problem reading Wikipedia of a recently released film and watch it with my friends later, or play a game after watching a playthrough on YouTube. Therefore, I find it strange that some of my friends and my brother have any problem with this and bothered by it at all. I even had a friend who asked me “why do you read on even if anime has not caught up to the manga?” and “how are you able to enjoy anime even after you know what’s going to happen?”
I think people enjoy all these entertainment because they don’t know what’s going to happen next. They are getting the thrill of not knowing how the plot will go, that’s why people (especially my friends) emphasise on plot twists and enjoys them so much. And to them, it seems like I’m ruining the fun for myself by spoiling myself. So I think what my friend is really asking is “why do I enjoy shows if you don’t get the thrill of not knowing what’s going to happen next episode?”
It is true that I don’t usually get the thrill from these types of anime. However, I’m still fine with that because I’m able to enjoy the other things in the anime such as music, voice acting and visuals (especially if they are done right.) for example, at the time of writing this, nearing the end of summer season of 2014 and from the series I follow, I have read through Sword Art Online and Akame ga Kiru! Therefore I know what is going to happen in next episode, and I am totally fine with that because I personally think both are nicely done anime with quite good visuals, soundtracks add depth to the situation and good voice acting makes it feel like the characters are real, and not just a character from a fictional world.
For example, there were scenes in SAO season 1 where Liz and Kirito went on a mission, I appreciated the art and visual work done by the animation team that I won’t be able to appreciate just by reading words on a paper, and there are occasions where the visuals are better in anime compared to manga such as Attack on Titan, the only manga where I still have not gotten used to the art style. Good soundtracks and music from different anime set the atmosphere perfectly and convey its mood to viewers. Fast paced action in Akame ga Kiru!, or sad moments in Inuyasha won’t be same without their soundtracks (Theme song for Kikyou is still by far my favourite theme song.) Even if you know what the character is going to say next, hearing the character speak feel much different than reading the line the character says in manga or light novel. Portrayal of emotion of a character feels like more effective when you hear characters speak rather than reading the line on a book.
Another benefit of reading the source material is that then I know which anime to avoid watching. I have dropped Fairy Tail 2014 from my list because I know how boring this arc will be so I won’t be watching it.
Because of these reasons, I am able to enjoy anime even though I know the plot twist, character development and anything that can be major spoiler. Or rather, that is why I can enjoy anime more because I have one less aspect of the show I have to concentrate on. I can get all the thrills before watching anime so I can concentrate on other important aspect.