Freeze, that's a dumbass reason. We considered Pluto to be a planet because we thought things were different to how they actually are. We've now found out otherwise, so we've changed stuff. Science moves on.
I'm sure all those people writing scientific journals were jolly pissed off when it was proved the Earth was round, or that the planets orbited the Sun, but it'd be stupid to not change things simply because it's a hassle and people have thought that way for ages. (I'm aware that's a slight Straw Man argument there, but I think the logic still holds.)
Pluto wasn't even discovered that long ago anyway. There's easily a few people alive who could say "When I was a kid, Pluto wasn't a planet because we didn't know it existed".