Why were Sodom and Gemorrah completely destoryed in the bible?

Sodom and Gemorrah.  Two places we will never see again.
I have to say that its quite a scary story. One thinkgs that it is all the sin of these two places that was so bad.  What could it have been?  I have read that the fact is that they were stealing from one another in excess and as a common way of life. 
This is the sin that we have here.  Not just theft, but assumed normalacy of theft.  The fact is that in today's society, theft is considered a no-no.  It is always meted with anger and it always creates strife. 
In Sodom and Gemorrah, the thefts were such that if you did the theft, noone condemned you and you were free to steal anywhere you wanted.  It created a system of victimization that extended throughout the confines of the city and into the universe. 
So it is my belief that Sodom and Gemorrah absolutely had to be destroyed in totality.
True there were the gamut of sexual sins and the like.  But those are still found in societies today.