Just speaking for myself, I think the return of people to the Moon has a lot to offer for understanding the formation and evolution of terrestrial worlds; so would the exploration of near-Earth asteroids by people.

Discovering that our solar system has many more planets than we ever expected, and that most of them are ice dwarfs rather than like Earth and the other rocky terrestrials, is just another step in the revolution in viewpoint that removed the Earth from the center of the physical universe and makes Earth all the more special.

Of course Pluto is a planet: It's massive enough to have its shape controlled by gravity rather than material strength, which is the hallmark of planethood.

Alan Stern Quotes