Thinking of extending that trilogy past its prime? I think it's important to realize how an especially bad turn in a film series can hurt the legacy of the entire series to the point where it might damage the director's reputation and the retroactive reputation of films that come before it.
As a 12-year old kid, I loved Batman Forever and I recently went to look up reviews of it. Before looking them up, however, I had a preminition that because of the disaster of Batman and Robin, Batman Forever would be seen as much worse than it actually was.
While Batman and Robin extends those "campy characteristics" to an extreme, without extending any substance to them, I think it's important to note that Batman Forever had a stopping point to its corniness before it ever interfered with the story at hand.
Furthermore, It's important for everyone to realize that since Batman's creation in what I believe was the 1920s, there have been two parallel versions of Batman going on. One is the "dark knight" Batman, the mysterious force of good who no one knows about, and then there's the "camp" batman, who's more family-friendly, and more colorful, put it that way, his costume has blues and purples in it, rather than just plain black. The key difference, when you think about it, is Robin, because with Robin in the picture, Batman is nowhere near as mysterious and extraordinary because there is at least one other person doing the same things he is and there is at least one other person who is fighting the same battles he is, and also because Batman has to watch out for someone else, you know he's not selfless and evil. The people who like the "dark knight" Batman, are probably people whose prime hobby is comic book collecting over film watching, because that's where the dark knight first appeared.
Me, on the other hand am a film watcher who was born in 1983, so when Batman Returns came out I was 9, and while the depth of Burton's dark urban vision was so extraordinary even i could be amazed by it, I had a hard time with all the violence, seeing so many of Penguin's henchmen killed (a couple at the hands of Penguin, himself) or the scene where catwoman robs a store and kills a guy with her fingernails, etc. I'm not saying I needed a happy ending, but all the characters, even Batman, were just very depressing.
When Batman Forever came out, I was 12, and unlike its predecessor I really got on board the ride, because the movie had really great heroes and villains, which i could be engaged rooting for or against. In Batman Forever, Batman and the villains are all equally perverse and dark, I really didn't care much who won at the end, and maybe people who are harsh on Schumaker's films fail to take into account what these Batman movies are like for a kid's perspective.Visually, the movie was a marvel to watch. Tommy Lee Jones' make-up job is so great, i'd like to see someone tell me they weren't blown away, the first time we see the left side of his face in the film. Some people say that Tommy Lee Jones' portrayal of Two-Face wasn't true to the original character, who was a less hysterical individual, but I think a more composed and cool villain wouldn't have been as fun, simply put. The Riddler/Two Face partnership is the best mildly deranged villain/completely deranged villain chemistry in the series, I found (especially considering the other two partnerships never really had very much interaction with each other). Just look at the movie poster for this movie and the colors of the riddler's green, two-face's purple, robin's red, batman's dark blue/black. Like a John Williams score associates musical themes with each character, those colors with surreally bold hues draw out the characters throughout the movie. Also, Nicole Kidman blew me away too. This was long before she was in a stage where every movie role she took was basically crying out, "give me an Oscar." And as for Val Kilmer vs. Michael Keaton? Well, I think the best person to answer that question would be original Batman creator Barry Kane (did I get the name right?) who aid that Val Kilmer was the actor who played Batman closest to the vision he originally conceived it to be.