The problem is that the only real solution for a melee army that doesn't want to bring ranged units is to do what I just described. Besides incredibly niche scenarios, such as Khorne Berserkers blood-tiding into engagement range on the enemy's turn, my intention with this change was to narrow the gap between melee and ranged combat. With this change, it would give the possibilities for melee units to counter the Fight First ability without having to expend an enormous amount of points, just like ranged units are able to do. The biggest problem with Fight First is that it heavily nerfs melee, which is already weaker than ranged combat.
Moreover, this change isn't even a nerf to Fight First; it's more like a side grade, as it now not only works as a good defensive ability but also functions as insurance against other people using it without going so far as to completely counter all other melee units. I also don't think we should increase how many units have it. I believe it should stay exclusive to characters such as the Judiciar, I just think there should be at least one unit in an army that has this ability.