OK I’ll bite. What was their political motivation for reclassifying Pluto as a dwarf planet?
A group of foreign a-holes suddenly wanted the huge controversy (/sarc) about the definition of planet settled, otherwise the entire science of astronomy was going right into the bin (/sarc), and they just happened to concentrate their fire on the only planet that to that point had been discovered by someone in the US. The first proposals were too hostile, so a compromise was reached.