What is the significance of how the American federal system decentralizes our politics ?

There are a number of significances to this fact.  Among
them are:

• It protects against tyranny.  One
  reason for the creation of a federal system was to prevent any one part of the
  government from having too much power.  By decentralizing power, our federal system
  helps to protect us from having one part of the government become too strong at which
  point it could tyrannize us.


• It offers more points of
  access to government.  Because there are multiple levels of important governmental
  actors (federal, state, etc), there are more points at which citizens can try to affect
  what government does.  If power were centralized, there would be fewer points at which
  citizens and interest groups could hope to talk to governmental leaders and try to
  influence them.


• It offers more opportunities for policy
  innovation.  States have been called the "laboratories of democracy."  With a federal
  system, we have multiple states that can try different approaches to solving problems. 
  In a more unitary system, we would not have this
  advantage.