From The Screenplay Novel Manifestos 2

 Q: So you’re saying that just because the idea of a screenplay story hasn’t gained popularity in the literary world, that it’s a good idea simply because it’s new?

A: Ideas aren't good simply because they're new. I might be the first person to invent chocolate-flavoured cheddar cheese. That doesn't mean it's worthwhile. Instead, I think this idea is good because it has the potential to work. It solves problems for the writer, and solves problems for the audience. It's quicker to produce and quicker to read, yet at the same time, it keys into people's imaginations. It is a very effective way of creating the vividness necessary for a story to "work". At least, this is how it works for me. Some people don't feel the same way. For them, it's not a particularly evocative way of writing. They need more description -- both of the environment and of interior consciousness. I understand this. Because the screenplay-novel is stripped-down, it seems to have certain inherent shortcomings, one of which is less physical description and the other which is the apparent disappearance of interior consciousness.

The first quality can still exist in a screenplay novel. As in a regular screenplay, there is no necessaryrestriction on the amount of physical description that exists. There are simply conventions; screenplays tend to be very minimalist. However, a screenplay-novelist doesn't have to follow this convention. He or she can include as much description as he or she wants.

Evoking interior consciousness is more of a problem. Interior states of mind don't "disappear" in a screenplay-novel. Instead, they have to be evoked mainly by the characters' dialogue. (This is one reason why I tend to use more description of gestures, facial expressions and tone of voice in my dialogue than you'd find in a regular screenplay.)

The screenplay-novel form is not perfect. It has strengths and weaknesses. But let's be honest: the traditional novel has inherent short-comings, too, not the least of which is its decreasing popularity.

Call the screenplay-novel experimental literature. But it's experimental literature with practical aims.