What were you expecting for $400, given that the $800 iPad Pro has, I quote, "4-speakers, 4K 60fps, 12mp camera, portrait mode, ProMotion" and FaceID?
Unless I'm misunderstanding you, and that you'd rather pay $600+ for those features on an iPad mini?
I certainly would pay more for a device this size or a bit smaller but with a larger screen (i.e., no bezels), Face ID, and Pencil 2 support. I don't care about the camera and have no idea what ProMotion is, but a high-end Mini would be an instant buy for me.