A primary antagonist, even if their face is somehow concealed, will likely have a very distinctive appearance and a considerable amount of dialogue. After all, they lack a name and other distinguishing characteristics (sometimes they don't even get a face) as a result of the Law of Conservation of Detail, so they also have no identity or soul.
Why? Because Red Shirts and Mooks are not generally seen as people. In fact, an entire Mook Horror Show is just fine.
When the hero confronts the Big Bad, no matter his crimes, he will spare him, despite all logic being against it however, when he kills a Mook who happens to be in his way, it's no big deal.
