These are not mutually exclusive concepts. An audience enjoying an action scene doesn't take away from the subtextual underpinnings of the narrative.
There's a point to be made about the presentation of violence as entertainment for its own sake. The visual arts often actively
ask you to react a certain way. It's kind of like when you watch a sitcom with a laugh-track you're more inclined to laugh at bad jokes than without it. When a film is presenting violence like a choreographed ballet it is asking people to gloss over the loss of life and view it as kinetic art. Compare that to, let's say, how violence is presented in A Clockwork Orange, where the film offers a direct examination of our relationship with violence on and off the screen,
where a connection seems to be made between Alex and the viewer.
As much as Snyder visually glorifies violence overall, when it came to the Zod neck-snap scene it was really done to attack the core of our cultural expectations that Superman maintain a spotless reputation. It was an assault on audience expectations. That's not the kind of Superman movie I wanted to see, but I'll give it credit for doing something unexpected that got people talking. Superman as a spotless icon was just martyred in order to do it.
When it comes to Wonder Woman, Diana was raised as a warrior. Despite being fascinated by babies and appreciating the abstractions of love and peace, she doesn't seem to have the same aversion to killing that Superman does. So on the beach scene, even though this is the first time she actually had to do it, she doesn't have any moral ambivalence, before, during, or after. The only way the film singles her out is by making sure she saves Steve Trevor from the Amazon's vengeance.
Also, while the false-bad guy German was still a bad guy, after she realized he wasn't Hades, she doesn't seem to care that she just chased down and murdered the wrong guy.
The only time she really expresses mercy is by refusing to kill Dr. Poison, which comes across as somewhat forced.
I think if the film wanted Wonder Woman to value the sanctity of human life more it would have given her more of a sense of remorse about killing right from the start. But I guess you can chalk that up to being a key difference between WW and Superman's personalities. Superman is really supposed to be more of a lover than a fighter and WW comes from a Xena-like Warrior tribe.
At the same time, this sort of thing, taken as a whole, shows that the film has sort of a Spielberg Raiders style simplicity. It's not really concerned with examining these issues at such a level of seriousness. So to hold it up to that level of scrutiny is a little unfair.