Catalytic and secondary combustion stoves ('88 epa regs) did reduce particulate pollution and increase efficiency, but, it was not without it's costs. The cost of stoves doubled or tripled, the durability decreased, the cost of ownership increased, the controllability was dramatically reduced (esp. early secondary stoves) and they were often more difficult to use.
There is a point of even more diminishing returns - by including other, less commonly purchased appliances and further reducing woodstove particulate allowances, they are further increasing the price, increasing complexity and decreasing controlability ( the reduced ability of a stove to operate over a wide range of output - esp. slow burning/low output conditions). At some point (they are upon it), they will reach the point where further emissions reductions no longer increases efficiency, but, rather, decreases it.
EPA regs will never stop once they reach a certain level of emissions reductions - it's always a steady march past the point of necessity to the point of total control and madness.
As others have said, anything that allows people to be at all self-sufficient will be regulated, banned, or taxed out of existence. Sadly, almost no one is willing to go out of their way to stand against that.
Modern green environmentalism is the single biggest threat to the ideals of personal liberty and the philosophy of classical liberalism that the world has ever seen. I strongly believe that no other cause or ideology is so all-encompassing or dangerous as green environmentalism.