I am in the UK and have just fitted a RNS-E that needed "Coding" to the car. Without Vag-Com this would have meant an expensive trip to the dealer to sort out. In this case a friend took all of 5 minutes to confirm everything was working correctly and set up the Sat Nav on the RNS-E and the DIS.
To give another example, we often go to France and that means we have to adjust the headlight beams (we drive on the right side of the road - i.e. the LEFT!

). With Bi Xenons (Adaptive) it means a trip to the dealer to adjust and they charge approx $200.
With Vag Com it takes 2 minutes.........
Need any other reasons to get it?