Inside Pokemon anime, where villains are essential, they make an appearance being aware of the fact that Pokemon anime wouldn't come to existence if they weren't there. It's because they aren't usual villains whose appearance is limited to only 2-3 times. While the protagonists are stereotypes easy to understand, Team Rocket in the role of villains must be full of individualities and having sense of existence characters. Their existence must be made the way, that would make the audience to call out "I've been waiting for it!" when they appear on the screen. The more Team Rocket will be individual, the more they will stand out, the more Pokemon anime edition will differ from usual anime and become a unique thing.
In short, it's me who thought of making up a primary factor for Pokemon with existence of clumsy villains, "Team Rocket", appreciated by adults, transforming children-oriented anime into family anime that adults can enjoy too.