Did one ever know the reason why the pacing and story development change after Ash was hit by lightning in the beginning episodes? How Ash and his world were relatively normal until after the incident? I have a theory. The accident with the bike put Ash in a coma. Days later he was found and was hurried to the hospital and treated with heavy medications. This is why Team Rocket became less menacing. The medication took effect and stabilized his coma dreams, instead of being terrifying, they became idyllic, and he's able to live out his Pokémon master fantasies.

If one had noticed, the early episodes of Pokémon were of amazing quality. The rest of the series is just the results of his subconscious mind fulfilling his desires, as well as attempting to escape them. Should Ash realize he's in a coma, he would wake up, but suffer brain damage. So he has to take down all his mental barriers one by one until he can come to grips with what he is and escape his coma.