I note that Pluto is a planetary mass object (PMO), or planemo.
A planetary-mass object (PMO), planemo, or planetary body is a celestial object with a mass that falls within the range of the definition of a planet: massive enough to achieve hydrostatic equilibrium (to be rounded under its own gravity), but not enough to sustain core fusion like a star. By definition, all planets are planetary-mass objects, but the purpose of this term is to refer to objects that do not conform to typical expectations for a planet. These include dwarf planets, which are rounded by their own gravity but not massive enough to clear their own orbit, planetary-mass moons, and free-floating planemos, which may have been ejected from a system (rogue planets) or formed through cloud-collapse rather than accretion (sometimes called sub-brown dwarfs).
At the pressent time the planetary mass oobjects in the solar system includes eight objects classified as planets (including four terrestrial planets, two gas giants, and two ice giants), five classified as dwarf planets (including one asteroid and four trans Neptunian objects or TNOs), and nineteeen natural satellites or moons. And there are some candidates for classification as dwarf planets among TNOs.
And I think that most professional astronomers, amateur astronomers, and science fiction fans can list most of those planetary mass objects from memory.
So if I was an astronomy student studying for an astronomy career around 2006 I might be a little annoyed by the redefiniton of a planet. I might take the objection to increasing the number of recognzied planets in the Solar System and the redefinition of planet to avoid that as insulting to my ability to remember the names and data of a large number of objects.
Since the old definition of a planet left out the nineteen planetary mass natural satellites, continuing to use it would result in astronomy students and school children having to remember the names of only fourteen planets so far, with another five presently considered strong contenders to be classified as dwarf planets or planetary mass object, and the hypothetical and as yet unconfirmed Planet Nine. So by 2021 there would be at most 20 objects listed as planets.
And possibly the largest trans Neptunian objects, the ones of planetary mass, could have been classified as a category of trans Neptunian planets, in a separate category from terrestrial planets, gas giants, and ice giants.
I also note that the dwarf planet and asteroid 1 Ceres, discovered in 1801, and the other three first asteroids to be discovered, were originally listed as planets. So after Neptune was discovered in 1846, there were usually at least twelve planets listed in astronomy books.
Actually the fifth asteroid to be discovered, 5 Astrea, was discovered in 1845, and at least one asteroid was discovered each year afterwards, and those newer asteroids were aleo often listed as planets. All the asteroids dicovered up to 15 Eunomia, discovered in 1851, were sometiems considered planets, until they were reclassifed as minor planets or asteroids in the 1850s.
So for a short period after 15 Eunomia was discovered, there were 23 recognized planets in the Solar System.
I also note that many science ficiton fans are familiar with many fictional planets, and that many astronomers who search for exoplanets around other stars may be familiar with many of the over four thousand exoplents which have been discoverd so far.