A. An increase in man days during bow season will 1) increase the harvest and 2) put more pressure on the herd. That will in turn piss off the gun hunters(THE MAJORITY OF HUNTERS) and they will lobby to shorten or do away with bow season. Many gun hunters would like to see that happen right now. I've heard those sentiments on several different boards, especially in my state. While many gunners may elect to hunt with a xbow, it will never replace their love and choice of the gun, thereby, IMO, cancelling out any support gained for archery. The bottom line is this, if it hurts the gun season, it will not be supported by the main stream.
I understand your skepticism and I am sure it's the same thing that people here thought. However, I honestly don't think it will be the case. I know it certainly hasn't had that kind of impact here. I don't think it will there either.
B. Opens the door to other weapons and a future of multi weapon seasons across the board
Again I have to reference Arkansas where we have had a crossbow season since the mid-70's haven't had any such laws.