Ever heard of Dragon Ball? Remember how super popular and well received Gohan was as the main character?
Yeah, neither does anyone else.
If you switch out the protagonist every few years, you send the message your cartoon doesn't matter because it's not worth investing in the leads. A fair few people can probably name the main characters from the original Digimon series. How many do you think can name the ones from the more recent ones? How many can identify Ash Ketchum?
This is from the same school of thought as "If they aged up the characters, The Simpsons would be good again" It's asinine.
