>>52901650This recent video helps explain part of it.
https://youtube.com/watch?v=WyvfKFVRqVs&feature=sharesAside from percussion, only 3 music notes could be played at any one time on the Gameboy. Which meant chords were usually out of the question. They HAD to invent counter-melodies that weaved into the main melody in an interesting way or the song would sound like shit.
I also think there is something to be said about old video games in general. They didn't have a bunch of reverb or modern synth-y sounds, the audio quality was not great. But because of that, the contrast of each note was greater. It's like hitting a note on a marimba hard and fast, making a harsh but stand-out noise, vs modern techniques hitting the same note slightly slower and softer to make it "smoother to listen to", but when you do that the melodies do not shine as much. Compare the original RBY Trainer Battle theme with all the later remade versions of the same song. Even if it's literally the same composition, the dramatic melodies don't stick out nearly as much.
