Traditionally, "planet" meant "wanderer". And pluto still wanders around the solar system. With the traditional meaning, it is still a planet.
As you indicate, the real change was to the definition of "planet", which has now been made more precise. And science does periodically refine its terminology and improve its definitions.
A lot of scientific change is really change in definitions of terms and concepts. So the change of the status of pluto is really a pretty good example of scientific change.