Pokémon - Team Rocket's character development

That's because Black and White took off their personalities in exchange for nothing. All of their plans failed as they always do, just in a more "serious" way. Heck, one of their plans took 6 or 7 episodes to make, yet it blowed up because their helicopter was attacked by one single move and exploded.

They did gain points for saving the boss (which was at the end of Operation Tempest, not Episode N), but not because they were serious and boring characters. They also won points in Diamond and Pearl for helping defeating Team Galactic (they took all credit for it, but it's not like they did nothing), and they were comedic back then.

The same goes for when they rescued the twerps from Team Plasma, and now in XY they'll fight against Team Flare, all while keeping their personalities.

Also, while they aren't as close to the boss as they were in BW, seems like they're being provided with better technology from Team Rocket, and they're getting paid better. They use a sort of hologram as a Pokédex instead of James' cards, and they don't starve or fight over the one cookie they could afford anymore.