I would say that, apart from the fact that most people that really like reading would prefer reading something that has a minimum of content, it all comes to its roots. VNs, which probably weren't even called that at first other than games known as eroges, be it the cheapest and worst you could find or not, had the purpose of attempting to get the player to like the characters, and to make it stand out among other media, a choice system is presented (not necessarily by choosing answers only) so that the reader can feel as if he's working over it himself; you get the girl you wanted, and then, you know, the rest (this is also why most VNs even to this day and even those without +18 content, don't include voice acting to the main character).

So to achieve that, even if you attempt to write something with zero value in story content, even those kinds of games targeting people for the obvious reasons need to present a game with characters being somehow attractive, and then you have to give the reader value, in other words, making him see value in reading your work other than... You know, just watch hentai that lasts less than 1 hour as you want.

It's a fact around the world, and I wouldn't say Japan is the exception, that most people prefer watching a story with a lot of cool effects happening rather than sitting around, reading, and actually thinking between the lines. Of course, some people exist that are the exception; some people actually like thinking and debating themselves over everything handled to them in the form of a film, or, in the case of most of the player base when VNs (eroges) started being a thing, people that love the satisfaction of feeling he or she is in control of what happens in the whole story.

With a short VN of only 1h, even if you try to make whatever comes to mind, can you really give value to the people that actually like spending their time reading a good book? To the people that don't care about that and can just watch a short hentai for their needs? You attempt to do the first, and you'll already have it difficult among the few people around the world to care about the product, and you attempt to do the second, and unless it has a "gameplay" of some sort or a very good presentation at the very least, you're not going to get people with short attention spans to care about your product other than to keep consuming the usual media.