But it was just because the CGs were all designed from a 1st person perspective. While we never saw him, he wasn't blank. He had a (complex and deep) past, a personality relatively clearly defined, and few goals (some being dropped before the end of the game).
The issue with WVM is that the MC is really, and literally, faceless, strictly speaking. When the CG include him, either there's something (generally a girl) blocking his face, or there's a big black square in place of his face. Some other games do the same, generally using a troll face or a smiley, what is just a bit less ridiculous.
Smiley faces? Never seen that.
I think that not showing the face can have a purpose. It really depends on the story.
To me most games, while lewd, forget logic and reason.
In that case it doesn't even matter if the MC is faceless. It wouldn't change the game.
I never played WVM. Maybe i should check that.
There was a game where i thought it had potential but it wasn't great in any sense either. Though it triggered the lewd desire in me. Clearly when hormones go in your way, you can't think anymore.
What i could envision is scenes where you would see the MC in a mirror but clouded in fog, blurry. I think this can enhance the experience.
I think there is potential to developing a protagonist that you don't actually see.
Most are more like an Ed Wood movie.
If the game shouldn't be your usual porn game, then it is important to know what it is about. Why does this story exist and why the protagonist is important to the game, the story.
To show him, or not, is in my opinion secondary.
It shouldn't be some, as you said, troll face plastered over the face but something nuanced. Where you get a hint and you imagination can take over.
I think the worst movies are those that give you all the answers. No thinking required which is in most porn movies or VN's.