It used to be said that Pluto is a misfit. But now we know Earth is the misfit. This is the most populous class of planet in our solar system and we have never sent a mission to this class.
This is in a real sense the capstone of the initial missions to explore the planets. Pluto, its moons and this part of the solar system are such mysteries that New Horizons will rewrite all of the textbooks.
We're just learning that a lot of planets are small planets, and we didn't know that before, fact is, in planetary science, objects such as Pluto and the other dwarf planets in the Kuiper Belt are considered planets and called planets in everyday discourse in scientific meetings.
Naming celestial objects is usually done by astronomers and professionals. Other people who are interested in space never get the opportunity to do that kind of thing.