The plate also makes it easier to clean as without it peoples handprints will be in a wider area. For wood doors its even better as wood can be time consuming to clean well.
I always avoid touching that metal door plate, I've gotten 'stainless steel cleaner and polish' on my hands too many times for me to consider using it again.
Now that you mention it, I do the same unknowingly. I always go for the wood above the plate, just because unconsciously I think it's cleaner than the metal plate.
