Then she has the agency of choosing her Volley complication; either (a) less damage, (b) spent Ammo (which she couldn't much afford at that point), or (c) danger.
When she chooses danger (which is very common in DW), my menu of options for that danger opens up dramatically. I went with the above, but due to all the pieces in play that I control and the (non-binary and multi-vector) nature of the system's machinery (resolution mechanics, tags and resource attrition/status effect system, and fictional trigger requirements for moves), I could have made probably a good dozen or more distinct moves that would changed the situation, observed fictional positioning continuity, observed the GMing principles and the games agenda, while escalating the threat level and introducing a new, interesting decision tree to one or both of the players.
So, on the strength of (1) and (2) above, my creativity does not feel particularly bridled when running Dungeon World (neither in the moment nor long term)!
Ok so looking at this and referencing the DW SRD... the player (because remember I was speaking to GM/DM creativity) decides what the out come will be from their move either less damage, spent ammo or danger.
Now let's first look at the example where the player picks less damage... With this choice I see no area where the GM gets to express any type of creativity. It's less damage, pretty simple and straightforward. I guess color is a form of description and the GM could describe less damage in an exciting or colorful way but I think it's quite the stretch to in any way call that the exertion of unbridled creativity on his or her part.
The second option...less damage is even more constraining on the GM's creativity it doesn't really allow any at all.
The third option...damage... okay finally we get something the GM can use... of course again this seem more to revolve around color as opposed to any real unbridled creativity. I can describe the damage how I want but at the end of the day it is still just damage.
So looking at this example I feel there are a couple of points of constraints on the GM...
1. The point at which the player decides what consequence they wish to take place due to their roll... So the DM is constrained by the fact that he doesn't get to actively pick which of the consequences (even within the parameters of the 3 set forth for the specific roll in the game) affect the player. Instead the GM is constrained by the layers choice.
2. The point at which one of those 3 consequences, as chosen by the player, take effect. Now the GM has IMO two points of constrain
a.) Point 1: The player chooses less damage or less ammo... the GM really has no route to express creativity in this instance. These are player facing results that have are chosen by the player and leave little if any room for unbridled creativity.
b.) Point 2: The player chooses danger, well the GM does get to flex his creative muscles in that he gets to decide the type of danger and the fiction surrounding it but again he is constrained. The adversary can't run, can't negotiate, can't try to bribe the character and so on. This is what I am getting at when I say constrained creativity. In D&D I am not, as DM/GM constrained in this way. I can choose to respond to the PC's attack in a multitude of ways that still fall within the rules of D&D that would not be available to me if I am following the rules and moves of DW.