@iMaple
From personal experience, when I judge parts of myself, what happens is they "submerge" and are still part of me. They still are visible to everyone else, and still impact my actions, in some cases significantly. I just am mentally plugging my ears and going "la la la la" when the trait shows up. I think the song "Let It Go" is specifically saying to stop doing this --- blinding yourself to parts of yourself because you don't like them.
Now, once you accept everything in you as it is right now, THEN is the next crucial step. That is when you can say "OK, this trait is unhealthy for me/loved ones/makes me unhappy/etc" But, throughout the entire process of changing that trait, it's crucial to accept the present reality, at the same time you're gradually changing it. It takes time to change something, and it's not a linear process --- sometimes I've made great strides in something, then had a sudden setback. I tried my best not to judge it, and continued working on it.
So I agree 100% that it's silly to just say "Enough of this, I'm outta here!" But to change yourself, you need first to KNOW yourself, and you can NEVER know yourself if you judge how you are at this moment. And that's easier said than done.
On topic: When I've had a very bad day, I sing karaoke to some of my favorite songs, eat some chocolate and pet my kitties.