I get that reading a visual novel written entirely in nvl can get annoying, but while the adv textbox is perfectly adequate for character interactions and small pieces of narration, I do think that tasteful use of nvl for longer stretches of narration, particularly to distinguish a third person narrator from the characters perspectives or signal that something unusual is going on, is a benefit to the presentation and can heighten the impact of the story being presented.
If you do make use of both formats though, you need to write with that in mind, so you aren't constantly switching back and forth.
