Monster Hunter isn't popular world wide because Americans have been babied by their games. Most people don't play as many challenging games now days. I'm not saying everyone, but they had to drop the difficulty level significantly for people here in the U.S. to even want to look at it.
It's also suffered from bad advertising overseas since the PS2. Bad advertising and bad reviews, I suspect because the reviewer of Game informer got demolished by a giant, pink, featherless, fire-breathing chicken and then decided that he didn't want to play anymore.
It was Nintendo that helped them fix their advertising with Monster Hunter Tri but the series was slowly gaining popularity with it's PSP ports before it.
Pokemon is the bigger cash cow though. No question.
I am guilty of being an insufferable smart ass! Too many people I know would be perfectly content to burn me for a witch.