[bawolff]

It could also be the degenerate case of something good. E.g. feeling withdrawn and unmotivated can be good sometimes - it can tell you something is wrong. Depression is like an extreme version of that. Maybe its the brain taking things too far and getting stuck in a bad state or something.

I dont know, IANAD, but it sounds mildly plausible.

[anoncake]

Yes, feeling depressed can be good. Just like sadness and other negative emotions. But depression, the disorder, is not.