I can understand why folks downvote and I respect the reasons for doing this.
It seems to me that when a question is at -2 and someone downvotes it further, that this down vote is crossing a line. Unless there's a legitimate point, this strikes me as just plain mean and aggressive.
This is not an issue that directly affects me as a user. In my case, I usually delete a question if it gets to -1 so this is not about me.
This is an issue that affects me as a member of the math stack exchange community. I do not believe an educational community should be unnecessarily harsh or disempowering.
This relates to questions such as this: What are the likely fruitful approaches and challenges to be overcome, when tackling this Group cohomology representation of the Collatz conjecture?
I voted this one up not because I felt terrible that this question had been downvoted to -5. I am glad that its rating has moved upward.
In my view, the question ideally should really be at 0 if people feel it is not of value and in negative area if there are changes that are expected or if the author could have spent more time before asking the question.
The anonymity of downvotes allows them to be quite cruel. I understand that there are questions out there that legitimately deserve a lower number than -2 so here's my proposal:
Can we make it that to downvote a question that is already at -2 that we require a justification of a minimum length or a flag of spam or inappropriate content. If a person doesn't feel strongly enough to provide a justification of mimimum length or a flag, then I suspect that the downvote past -2 is probably inappropriate.
If a question does deserve to go to -3, then let the person who makes the downvote justify it. When anyone sees a question with -2, they get the point that this is not an authoritative question.
Does this sound reasonable? If I see a -5, I really expect to see spam or someone who asks a question that is completely outrageous. I don't expect to see a question like the one that I referenced.