Thanks for adding this. I do agree. You have hit the nail on the head of why the more common phraseology is the wrong way to go. It does invite the affirmative; you know the research adage that says, never ask a question in a manner that directs the answer.
Although depression is treatable and curable, or at least "overcomeable", the depressed person does not feel that way. They feel that they are stuck forever and ever in this state. Which is often what drives suicide. As you point out, one would never say to person with a life threatening illness or injury..... are you feeling better today? One would phrase it in manner such as you suggest. I should have considered a follow up paragraph on suggested phraseology.
Depression steals hope and without hope one feels they will never get better. That is why it is so common among those involved in issues that deal with the injustice, pain, and sadness of the world. As you point out, it is common among animal advocates and activists as well, particularly when no one else that one meets in the day to day business of life feel the same way or deal with the same issues. That is one of the reasons that this list is so helpful. I am not alone, you are not alone, we are not alone.