Nothing is more permanent in politics than temporary solution. As a Norwegian, for example, I am still paying a temporary 25% on all spending that was enacted as a "temporary" measure over 100 years ago.

Control Theory does not work (in the general) for politics for the simple reason that incentives are misaligned. That is to say that control theory itself obviosuly works, but for it to be a good solution in some political context you must additionally prove the existance of some Nash equilibrium where it is being correctly applied.

Edit: See https://www.youtube.com/watch?v=rStL7niR7gs (CGP Grey - Why Do All Governments Work the Same Way?)