Back to the original topic, I think there may be a tax revenue motivation behind the increase. In addition to the fact that $800 USD per month isn't really enough to live on here, an income of $800 USD per month does not subject a temporary resident visa holder to taxation in Argentina. $2000 USD per month per person certainly will.
I never met or even heard of a foreigner living in Argentina with a visa rentista who was paying income taxes in Argentina, With the new income requirement that will probably change. Who knows, in the future migraciones might require receipts from AFIP showing tax payments prior to granting a renewal of the visa.