I think they did this because when Pluto was discovered it was the only thing in the Kupier belt we knew about. Now that we can see further into the belt we are finding that there are literally hundreds of "rocks" just like Pluto there. So unless you'd like our solar system to contain about 80-100 planets eventually, it is best to eliminate all the ice dwarves from the beginning and not worry about it later when we are finding hundreds of other "rocks" like pluto.
I really think its childish to believe they demoted Pluto because of a poll...lol As if scientists care what the people think.
Its not really sad. I think something is sad when you have overwhelming need for a change, yet you take an old belief and stick to it no matter what, even if you don't have any evidence to prove anything(i.e. religion). Science is everchanging because it is -willing- to make changes, and even correct things it believed to be right in the past.
PS. Sorry if my religion comment offends anyone