The advantages of using VST over a real drummer are many. It is cheaper....you can get exactly what you want and not have to rely on live drummers foibles or styles..you have almost infinite different kits and styles to choose from....you can control the final output of each drum or cymbal track by track rather than a bleeding leaky mix where mics pick up all other drum sounds. It is getting more and more harder to distinguish between real drums and virtual or sampled tracks. Ok it takes a bit of setting up to begin with but once done you have the templates forever.
All that said there is nothing like playing live with a real band using real instruments......sadly in recording that is almost a thing of the past.

http://www.soundclick.com/bands/songInfo.cfm?bandID=687727&songID=5238055