...Seriously does it make life easier for them or something?
I think in many cases, it does make life easier. JWs don't need to think for themselves, Infact they are told that independent thinking is divisive and idolatrous (in that it elevates oneself above the FDS and, in some cases, even Jehovah himself). For them and others who shun/avoid/'look down on' it helps them keep focused on their primary goal in life, whatever that may be. They have formed or adopted a belief system and life goal or life style that is dependent on that belief system.
What would make them change?
Many chose not to change even when faced with extreme evidence that change would be in their own best interest. Often it is an unexpected humbling life experience and subsequent kindness extended by a former 'shunnee' that allows them to see the error of their ways. Unconditional love conquers all - sometimes.
And most importantly when is it right to shun or is it really right at all?
Time and place maybe?? If I am on time crunch and too much to accomplish and I notice that there is someone who wants to talk and talk and talk to me and will not respect my words when I say 'no, not now', I think that is an acceptable reason to shun them in that moment (ie: walk down a different aisle at the grocery store or not take their phone call). Someone who constantly ignores clearly established boundaries can be denied entrance to my home but it is not loving to completely cut them off from my life. Someone who has been physically, spiritually, emotionally, or sexually abusive to me (or my loved ones) can pretty much count on being shunned by me at nearly every turn. But is that really 'shunning' or just strong boundaries?????
-Aude.