When building an exhaust system, what is the benefit of a crossover pipe when applied to Ducati Monsters?

I think that one cylinder exerts a different amount of pressure then the other since one is shorter than the other.  The portion that is crossed over allows for extra pressure from one pipe to be transferred to the other at the crossover point which is "hollow".  So in that sense at the crossover point the two pipes become "one pipe" then branch back out to two pipes.   

http://www.monsterparts.com/pc/M0119DT1/Exhaust/M0119DT1.html