Poorly-Aged Franchise

''But not like some disease that'd cause your skin to go yellow and give you an overbite. Not that kind of Simpsons' disease.''

Simpsons' Disease is a somewhat uncommon condition that causes franchises to lose sight of what made them so likable when they were new, therefore throwing them into a Downward Spiral until their audience either massively complains about the franchise or gives up on it entirely. It's called that because of obvious reasons. Simpsons' Disease normally spells death for a franchise as it causes it to either be cancelled by its creators because it's Too Late To Save their creation or become a Zombie Franchise if it's continued to be added on to with new installations. Simpsons' Disease can infect franchises much easier if they've been rebooted or given unwanted sequels.