Why are they no fun anymore, I like them better when they were always messing something up and "blasting off again".
This is because Team Rocket is essentially the villains, this is to make the younger demographic really despise them and root for Ash rather than anyone else. Also they have been quite serious since generation one. They put a gun to a man's head and gave James inflatable breasts (of course these were two episodes that were banned in the US) they just started putting them back to their roots.
