As a “visual novel person”, I can guarantee I would buy an upgrade that would have art in it, IF I like the artstyle, and that is an issue. Some people like realistic art, others like cartoony, others like manga-like… The artstyle can make or break a story too. For example, in a lot of cases I think “man, this story would be even greater with art!” - but when I see some cover arts, I think “man, I’m glad this game has no art if it would mean the entire thing would have that artstyle!”… so yeah, it really depends. I rarely like anything else than manga-like styles.
I also want to mention not all visual novels are worth $20+ - you can find free ones, some great, or ones that cost less than $10. And not necessarily short ones. But there is a reason why text based IF are longer than most visual novels on the cheap side. Art is time consuming, and with the amount of branching text based IFs require, it would be hard to make.
With that being said, yes, I know a lot of people who don’t like IF because of the no-visuals aspect, including people who bought text-based IF on Steam only to get a refund because “it’s boring”, so certainly, it WOULD attract new people with visuals. On the other hand, I’ve seen a lot of people in this community who are VERY unforgiving towards visual novels, so it could also loose fans, for all I know
With that being said, there IS market for visual novels that would have as many customization options as text based IFs, as proven by “Our Life”, which has to be the VN with the most customization I know. But as stated before, one couldn’t make a “visual novel remake” because of the policies, so it would have be like… an illustrated book, done with CS, I guess?
Surprisingly, that would be easier to an extent than a full visual novel, as long as it doesn’t have illustrations for every single scene. But then again, I’m speaking as a person who can draw, so it’s not the same as if someone had to hire an artist. I can just look at it from a workload point of view for myself.
If I was making an IF, I’d probably add more art to it, because I like it. But I’m not cause the visual novel format suits me better for a lot of reasons so yeah.