The goal is not to remove green markers with the hotshot gunner, which vader has already removed before. He's pretty useless for that. One could take another target than the Vader target, but that contradicts the credo to make focus fire. The opponent often has no token at all because of the blocks and Vader.
With the agile gunner you show the opponent quite strongly what you intend to do in the next round.
As I said - the list has a development behind it and the components in it have crystallized and all have their uses.
The veteran gunner is exclusively against lists with many ships and lists with many ships and little agility. You have to do extra damage or you lose the damage race. With every single damage or every use of a focus provoked by it, it has already been worth it.