Mokkai story, um impressive actors, director taking not great effort, only songs make some, mostly pretty ordinary situations as believable, impactful. Great song/tune makes even ordinary situation as very strong, impactful, believable. When we listen to some songs from movie we know nothing about, we assume great performance would have backed the song, but in reality, is simply wasted. Of course, there are many songs which are made good/deserving use of. Both the video and song complement each other and it becomes timeless and stands out for ever.
Sometimes, even idle actors are forced to emote becos the song is full of emotion, and a stone-face will spoil the song, and they fight to bring that emotion.