People already rarely downvote. (Well, except for those who do the mass downvoting.) Making the downvotes 5 times weaker, that's almost like removing them completely. Almost no one would bother.
What's your source for this?
Regarding making votes weaker and more expensive, I was thinking about that from the standpoint of 'downvoting in general is bad', and I would still bother.
One other possibility for downvoting might be the 'conversation of ninjutsu' trope: a person's downvoting power might decrease as the number of downvotes increases, so that one person can really only nuke 10-20 karma by block downvoting instead of an arbitrary amount.
Below is a message I just got from jackk. Some specifics have been redacted 1) so that we can discuss general policy rather than the details of this specific case 2) because presumption of innocence, just in case there happens to be an innocuous explanation to this.
So... thoughts? I have mod powers, but when I was granted them I was basically just told to use them to fight spam; there was never any discussion of any other policy, and I don't feel like I have the authority to decide on the suitable course of action without consulting the rest of the community.