How big a game changer is additional options?

Not unless they want players to combust and quit. After all, this current system at least lets you FoR until you get the stat you want and you can stick it on your character as long as possible so that you don't use up the scissors limit even if it's still crappy.

Edit: If I hoarded equips now and fused them when Unlimited rolls around, would my fused equips also have Additional Options?

Yes I guess. I don't see what will be stopping it from getting AO.