I'm looking at getting into VV vaping because I want to get the most flavor out of my juice.  I know that with a VV PV, you can tweak the flavor simply by changing the voltage.  For example, I was just watching a review of VapeRite's VR4 where the reviewer tasted a more caramelly-overtone and tobaccoey-undertone flavor at a lower voltage, and got the exact opposite on the higher voltage.   
  
Maybe that does make it more of a 'hobby' for some, but I see it more as searching for the perfect vape/flavor/throat hit.  For me, I like to find the best of everything (within reason and budget, of course).  If I'm going to vape, I want it to taste amazing.  I want to enjoy every second of it.  Unfortunately for me, I'm very, very, very picky.  I can taste the slightest 'off' flavor.  So, I figure with a VV PV, I can do some tweaking and therefore am more likely to enjoy most juices I purchase.