Who the fuck said anything about describing what you see on the screen?
You know that we are still talking about sex scenes, starting by your "
character's thoughts enhances h-scenes greatly", right ?
Character's thoughts, and internal narration, have nothing to do in those particular scenes. 90% of this could have been dirty talks, or could have been shown through the protagonist expression. At worse, but I admit that it's more difficult with Western VNs, it could have been shown through (audible or visible) SFX like in hentai.
Third-person omniscient narrator is the most common form in actual books
Except that
Visual Novels have something that books don't have. I let you guess what it can be.
But anyway, what literature are we talking about here ? In what stories exactly, from ancient Greece classics to modern literature, internal thoughts are as prevalent than in the badly handled VN relying mostly on them ?
Hey, in fact, in what stories internal thoughts are effectively present ? Oh, there's stories where we have clue regarding the thoughts of the main protagonist(s), but it's never effectively through internal narration or the display of their thoughts. It's more subtle like, "while he was leaving his office, Dick Tracy was nervously checking his gun, ensuring that he was fully loaded and that nothing would keep it stuck in case of needs" ; and not the stupid, "before leaving his office, Dick Tracy stopped. 'There's something wrong with this last minute rendez-vous, I should keep my gun ready', he thought", that we would see in VNs.
It's the principle of good story writing, "show, don't tell". Even if it's here through words, the author make use visualize the scene, and expect the reader to be smart enough to understand what this mean.
But anyway (again), internal thoughts and omniscient narration aren't at all the same thing. Omniscient narration is what OP called "cinematic approach". Through few paragraphs, or sometimes a whole chapter, the reader witness scenes that the main protagonist(s) don't know about. But while the reader will now react accordingly to this knowledge, the said main protagonist(s) stay clueless about what just happened.
Therefore, I wonder what this approach of story writing, that in fact isn't this frequent in literature, have to do with you trying to defend the display of the protagonists thoughts.
And the part about having sex... Dunno about you but I still retain my capability to think during intercourse.
And the guy being clueless about those thoughts, you say them out loud because it would be totally stupid to pass the whole time thinking "faster, oh god go faster you useless fucking piece of shit", and having him nuts before it even started to be interesting for you. Right ?