I have no problem with Snyder taking inspiration from Frank Miller, just so long as he takes away the right inspiration. For example, I love how Affleck's Batman looks like Batman from The Dark Knight Returns. This Batmobile feels at least partly inspired by the vehicle in that story as well.
I guess I should have clarified. I'm sure Snyder probably won't pull from Miller's more recent work on Batman, although the fact that he consulted Miller for this concerns me. I just hope he doesn't pull too much from Dark Knight Returns when it comes to drawing inspiration for Batman and Superman's dynamic in the film. In Dark Knight Returns, Batman is the clear hero and Superman is the villain. I'm not sure how I feel about Superman being the villain, but maybe if Snyder is acknowledging the end of Man of Steel it could work. I could see people hating Superman after the events of that movie. I could especially see Batman perceiving Superman as a threat.
I think my biggest fear is Snyder portraying Superman as an outright villain, verses exploring the dynamic a bit less one-sided. I'm sure Batman will eventually come to see Superman as his ally, so I'm not too concerned. I do question the level of consultation Miller has had on informing Snyder of his portrayal of Batman, though. Especially since Batman and Superman's dynamic in Dark Knight Returns is unique since they had a history of knowing each other for quite some time. In this story, they are supposed to be meeting for the first time. So it feels weird to draw inspiration from that story, unless Snyder intends to just take minimal and basic conceptual inspiration.
I'm probably not making any sense. Haha. I just want a non-psychotic Batman and a Superman that isn't an outright villain. One of the reasons why I think the Batman v. Superman title is interesting because I hope the v. alludes to more of a psychological battle between Batman and Superman in this film. Yes, I know we'll see them go head-to-head, but I think it would be really interesting if we saw Batman and Superman butt heads when it comes to how they achieve their goals, their values/beliefs and so on. Which is why I really want Batman to have a stance on no killing - because I think it would be a great contrast to Superman's lack of regard for human life in Man of Steel. Which is why having turrets on the front of the Batmobile bothers me. I like the idea of Batman, who doesn't kill and doesn't like endangering innocent lives, opposing Superman and the destruction and loss of life that we saw in Man of Steel. I feel like that could be a really interesting conflict and validate a lot of what many disliked, including myself, about Man of Steel.