Will DNPs walk into the exam room and say "Hello Jimmy, I am Dr. Smith"???
I guess MDs are doctors of medicine and DNPs are doctors of nursing so it'd seem somewhat appropriate although not traditional.
Tradition has a way of conceding to the dynamics of society. A few years ago, you would never think to greet your dentist by asking, "How are you today Dr. Smith?"--you would just say, "Howdy Smitty, Hows my favorite barber doing today?"