Put yourself in this position: Your whole life you've wanted a certain job. You've worked, trained and studied with all your effort in the hopes that you can have it. Finally, the day comes, and you get the job--Metalbending police officer. Then comes Amon, who, annoyed that you can do something he can't, takes your bending away. You didn't just lose the job because someone else could do it better, you lost the ability to do what you'd spent your whole life training for because NO ONE else could do it better.