Working on what's important rather than what you're told to work on assumes that you know what's important and that no one else is working on the important project.
Saying "this project isn't important enough for someone like me" won't just annoy your manager. It'll annoy everyone, because someone else will have to pick up the work you dropped. You'll get the reputation for being awful to work with, and that is toxic to your career.
Saying "this project isn't important enough for someone like me" won't just annoy your manager. It'll annoy everyone, because someone else will have to pick up the work you dropped. You'll get the reputation for being awful to work with, and that is toxic to your career.