WoTC essentially maintains 4 different lists: the max-0 list (banned), the max-1 list (restricted), the max-infinity list (basic lands), and the max-4 list (other). What if they added max-2 and max-3 lists? This gives them more tools to achieve their goals.
I would then propose bumping Mishra’s Workshop from max-4 to max-3. Compared to a full-on restriction, it wouldn’t cause as much economic damage to current owners, and would represent a more gradual approach to curbing Workshops strategies.