On a stellar scale Pluto might be right next to Earth, but it still 5 light-hours away, meaning roundtrip communication times from probes takes 10 hours.
On a human scale that's really, really, really far away. So it's not too surprising that we know very little about the tiny dwarf planet at the edge of our solar system.
And between them they have over 40 moons; some likely unremarkable rocks but others with observed or theorized geological activity, trace atmospheres, and unusual orbits and who knows what else.
Neptune is about 3 times further away than Saturn, and I believe Jupiter won't be in position for a good gravitational boost to get there for many decades. It's possible, but very very expensive.
On a human scale that's really, really, really far away. So it's not too surprising that we know very little about the tiny dwarf planet at the edge of our solar system.