Wonder Woman 1 also outgrossed it by about $40 million.
To be fair, I think the 176 minute runtime hurt it a bit. For certain people, that makes it less likely they’ll return for a second screening. I also think the Riddler’s visual appearance might have been another issue for marketing. Even the Nolan films had the villains stand out visually: Scarecrow with his mask that looks like the creepy child mask from The Orphanage (a Spanish horror film); Joker looking like, well, JOKER, and Bane with a redesign different from the comics but still visually distinct. Riddler in The Batman does not have a memorable visual look, granted it works for what the film is doing with its David Fincher-inspired style of story but it could have made people less excited if the threat didn’t really stand out in appearance.
I think Robert Pattinson’s casting also may have hurt it a bit. He’s well cast, don’t get me wrong, but a lot of people unfamiliar with his work outside of Twilight were doubting him. While people jumping to negative conclusions towards a casting in a Batman movie is hardly new, the thing is this was the first film of a stand alone series and the controversial pick was Batman himself.
With Nolan, he already established goodwill with Batman Begins, so when his at-the-time controversial casting of Ledger as Joker happened, plenty of people were willing to give it a chance even if they didn’t like the casting at first glance because Nolan had earned their trust. With Ben Affleck, the premise of Batman and Superman fighting was enough to draw in the fans even if some again weren’t sure about the casting. It was like Freddy vs. Jason, sure some of the F13 fans were upset that Kane Hodder wasn’t returning as Jason (as he is widely the fan favorite in the role), but they weren’t missing out on Jason and Freddy fighting regardless (and because a few smarties will point it out, yes Jason doesn’t talk, BUT plenty of fans prefer Kane’s build, body language, his positive input on certain scenes such as when he veto-d Jason killing a dog as he explained it had been heavily implied by that point in the films that Jason would not ultimately kill a child or animals, etc. Trust me, a good chunk of the F13 fans love Kane Hodder). But with The Batman, it was a new director (even if Reeves earned a lot of good will with his Planet of the Apes movies, not everyone has seen those and/or think that proves he’d also be good at Batman), new continuity, and a controversial pick for Batman himself. So I think it had the most uphill battle to fight out of all the Batman films since the 2000’s save Batman Begins (but that was primarily due to the prior Batman film, Batman and Robin, being infamous, rather than any casting Nolan made for Begins being controversial).
But yeah, while I would like to see both a DCU Batman film series and a Elseworlds The Batman film series going simultaneously, it makes sense to cut The Batman if they have to cut one. It did well, but not insanely well. But I don’t think it’s guaranteed they’re cancelling it yet.