Comments

I agree with your take, because I think visual novels are more like films/interactive series with user participation, you progressing on your own terms and interacting more one-on-one with the story being the main, if not the only, differences. You can't compare it to full-blown text only literature because it uses an inherently different skillset for analysis. It's like you said, you have to analyse the artwork in front of you, the audio, maybe even the colour choices and blocking in the artwork, alongside the text through what characters say and what the narration is. Because you have to take into account multiple elements that are just simply not there when it comes to text-only literature, it's very much like analysing a movie. 

You're analysing the composition through artwork and cinematography, you're analysing the usage of music, and you're analysing the writing through mostly spoken dialogue or through non-diegetic dialogue like a character's inner monologue, and that already puts it closer to films and tv series than it does to text-only literature :p