In the past, people use cameras by looking into the tiny viewfinder. When we have LCD screens at the back of our camera, people were laughing, claiming that it is stupid. Fast forward today, there are cameras not having viewfinders anymore.
Same thing here. Seriously, when you take a picture, why would a smaller viewfinder be better than a larger viewfinder? Having a viewfinder as big as the iPad is awesome. You no longer have to squint and guess what kind of details you would get from your picture. Having to squint and shrink yourself to look at a tiny screen is an old paradigm.