I would support the proposed lower limit. 
 While your thinking is most likely accurate, I suspect many who are moderately above the limit (say in the .09 to .15 range) thought they were OK to drive.  I believe that with a lower limit, that group who think they are OK to drive but are not, would eventually fall within a lower range, perhaps .06 to .12. Obviously these numbers are just examples to illustrate my point rather actual predictions, but I think my point is clear.