Revelation 20

This chapter describes the Millenium - 1000 years of peace on the Earth after the second coming of Christ.  During this time, Satan will be bound.  At the end of the Millenium, v7-10 say that Satan will be released to deceive the nations once more.  Apparently he will succeed in this, as v9 says he will gather an army to surround the "camp of the saints."  However, as soon as this evil army is formed, God immediately devours it with fire from the heavens and casts Satan once and for all into the Lake of Fire where he will be "tormented  day and night forever and ever." 

Here's the question I've always had about this (and I am assuming a pre-millenialist position)...  What's the point?  What's the point of the Millenium?  What's the point of Satan being released and being allowed to stir up trouble again?  Wouldn't it be a lot cleaner if God said, "Earth is done.  Sin is defeated.  The redeemed go to Heaven.  The lost go to Hell.  The end."  Why the extra drama?  Help me out here.  (And yes, I would like to hear from amillenialist and post-millenialist friends.)