RE: Is it necessary and what is/are the advantage(s)?
I'm with you on this one c903. I believe shot placement is paramont to a quick kill and speedy recovery. I don't care if you have a broadhead with a 3" cutting diameter, If you miss the vitals the deer may die but it will not die quickly.
It is also my opinion that a larger head may give the misconception that it is in fact more lethal to an inexperienced bow hunter. A seasoned bowhunter knows the importance of shot placement and bases his actions appropiately. If a shot isn't there, it isn't there. A lesser experienced hunter may force the shot because of the "new dandy mangle it heads".
Technology can only do so much. It is up to the hunter to decide when to shoot and when not to. When I shoot I'm looking for penetration first and foremost. I'm confident I can place the arrow where it needs to be and I want to inflict sufficent damage while still acheveing ample penetration.