Besides, if the goal is to inform policy direction, then there's certainly no reason to test every student or to make it "high-stakes". A statistical sampling, such as is done with NAEP, would be far cheaper.
There are also other ways to do assessment that do not rely on high-cost, high-stakes standardized testing, and provide a more comprehensive, though less quantifiable, look at student learning. Look at how Nebraska has done it (described in the book, Reclaiming Assessment )