I couldn't describe to you each individual plot point in a book I read last year. Whether you can remember every little tidbit of dialogue years later isn't important. While I'm playing, though, the plot line is right there in front of me, and all the previous bits and pieces are at the front of my mind. You throw in something that doesn't mesh with the plot in the least bit (i.e. Portal robot spheres in Skyrim, the talking dog in Skyrim, various other easter eggs in other games), that kicks me out of the game, and I don't want to continue playing. That's why keeping the story consistent is important, you dimwit.