Okay, I'm gonna keep it simple.If the question is what an Open-PvE mode would be useful for, I think the recent ShinDes CG is a prime example. AX pilots could wing-up in Open with no griefer obstruction. As it was, we had to use Block to control instancing, excluding gankers from AX instances one-by-one. Open-PvE would be a brilliant AX experience.
And there's the problem. Everyone knows this; it would be a no-brainer for all the AX activity to move from Open to Open-PvE. All the juicy targets with weaponry useless for fending off gank attacks would be gone from Open.
I took the forbidden mission because I want to be a pirate. I flew in, killed someone, and I'm a wanted man. Another person meets me and sees that I'm a pirate but can't do anything to me, my weapons don't work against me.