Why would people who love Batman fear a reboot? Wouldn't we all want MORE Batman, regardless? My response goes as so:
It has a lot to do with trust. I’ve grown up a Batman fan, I’ve lived through many versions of Batman (I watched the silly ’60s reruns as a toddler, BTAS as a child, Burton’s series, etc…) and what I think a lot of fans of BATMAN are worried about is that rushing into a new “reboot” will bring about the issues we had with Batman Forever/Batman and Robin.
There is a reason we love Nolan’s Batman so much, and I think it has a lot do with (at least for me) giving Batman the presentation he deserves by a writer/director/team of actors that actually understand it better than any other group has. I think Christian Bale said it nicely after Batman Begins: Nolan gave Batman his dignity back. What fans are worried about is that a new director with a less honest understanding of Batman may come along and strip him of that again.
There can be TOO much of something. There can likewise be a good place to stop and realize more could ruin it.
I’m TERRIFIED to see what the reboot does to this character I have loved for so long, especially after being presented with something like Nolan’s Bat-series. I am a fan of Nolan as a director, but what he did for Batman is something on a completely other level for me. It’s not because it’s Nolan that I love his Batman movies. It’s because I can see through almost every aspect of his Batman movies that he loves Batman as much as the fans of Batman do, and he’s trying to him justice for that reason. That’s a rare trait to find in directors. Even if they think they get it, not many do. Nolan DOES.
It’s trust. It will take a lot of convincing for me to trust anyone else with Batman. It just will. I've been burned before, I hope I can love again like I loved Nolan, but I can't make that promise.