It seems to me that reading a good amount is pretty critical for an aspiring writer. Just like how artists will see something that inspires them or musicians might integrate some element of one genre or band into their music, writers probably rely on what they have seen as a basis for what they can create. And the vocabulary helps, too. But if you want to be a good writer, you'll want to practice writing a lot. I believe Stephen King writes 10,000 words a day, even if said words arent ever going to be sold. As for the question about visual novels and light novels... I think that they probably help, but you wouldn't want to only read those. First of all, I would expect them to be missing some elements of writing that other formats may be reliant on. Second, you're reading translated works (right?), so it's not ideal. Variety is good.