Ya know, you almost made a very good point, at the end of your first paragraph.
However, I can answer for most of these people.
When Pokémon first came about, they all played the games and watched the show. Boy, was it fun. They had a great time playing cards, and battling their little pocket pals.
All was good for awhile. Pokémon was popular, everyone enjoyed it. In fact, everyone, except for a few, really loved it.
But then, time moved on. The fad wavered in strength, the popularity was dying down. Suddenly, people began to realize how much money they spent on their former pocket companions.
The realization led to anger, anger led to hate, and hate led to, well, more hate. You see, suddenly, it became cool to hate everything Pocket Monsters. Pikachu went from being everybody's best friend to public enemy number one. Who cares if the games were fun, it's cool to hate!
Some won't admit ever liking Pokémon, some will. Some have disliked it all along. It saddens me, really, the first games were actually quite fun, solid RPGs. I mean, that's what counts right?
I'm on the outside looking in; I don't hate Pokémon, but I never loved it, either. I played the games, and I had fun. Feh, if you want to hate it, go ahead, if you like it, hey, I don't mind. Just have fun, either way, while respecting each other's opinions.