Up until last Thursday night, I completely agreed with you. I thought that if an object had enough mass to pull itself into a sphere, it should be a planet. I thought the IAU's definition of planet was an offense to reason--well, I still think it is. Requiring an object to have "cleared its orbit" is a silly concept that would mean gas giants larger than Jupiter would be "Dwarf Planets" if they were found in a proto-planetary disc. The name, "Dwarf Planet," is completely stupid and offensive. How is a "Dwarf Planet" not a planet if it has "Planet" in the #$%^ing name???
Then, just this last Thursday night, I attended a lecture by the very engaging, highly-studied Neil deGrasse Tyson. The guy who declassified Pluto as a planet in the Hayden Planetarium exhibits long before the IAU did so officially. He explained to us that Pluto was mostly a dirty ball of ice... like a comet. In fact, if it were in orbit around the Earth, it would have a tail.
That took me aback. If Pluto is just a particularly large Kuiper Belt object--if Pluto is just a large comet that isn't close enough to the Sun to melt, then I must admit that it doesn't make sense to call it a planet.
This is a bit of an iconoclasm for me, so I'm still figuring out my position on the matter, but I'm leaning toward accepting that Pluto is not a planet, but that the IAU is a bunch of numbskulls who need to fix their illogical, nonsensical definition of "Planet" and take the word "Planet" out of their labels for things that aren't planets. This is the kind of political bullcrap that turns kids off to science.
Of course, all this could change when New Horizons reaches Pluto this July.