You must not put much stock into actors or their performances if you are happy to replace them as long as they have a less distracting visual appearance. I wouldn't give a toss if they got a Heath Ledger lookalike for TDKR because he still wouldn't be Heath Ledger. No actor could play the role the way Heath did because there's only one Heath Ledger.
Why do you think people are so against recasting a role? Unless the actor who originally played the part is truly terrible, audiences don't want to see recasts. Actors make roles their own if they're good at them. And needless to say Heath certainly fell into that category playing the Joker. The notion that someone should replace him in Nolan's movie universe is one of the worst ideas ever.
Hi there, The Joker.
I am totally sure almost no one casts someone if they're thinking of replacing him. And most of recasts are not a happy occasion either, I think. Most recasts probably happen when the actor doesn't work on the role, when they don't want to (or can't) return for the sequel or when they die.

James Bond was constantly recast, sometimes it worked, sometimes it didn't. I was expecting the third Batman movie to end with a bang, but Bane (and even less Thalia) couldn't pull it off in the villain department, which made me miss the Joker even more.
Now I'm not too sure if people get this is a new continuity and this new Batman and Joker are NOT supposed to be the ones they saw in Nolan's movies. Who knows how many are out there thinking this is Bale's and Ledger's characters recast.
But I'm sure there are worse ideas. Like a twist where Bane is not the mind behind the plot, a young policeman just guesses Batman's identity, he becomes its successor without proper training or knowing Batman that much and they name him "Robin" in the last scene.
Cheers.
The Joker was always a no-win situation. If a new actor gave the same performance as Heath, it would be in poor taste and come off as a knockoff. If he acted totally different, it would be a continuity error.
Regardless, I wouldn't have wanted a new Nolan-film Joker either way. Even now in a new continuity, my mind's still not ready for a new Joker. I'm looking forward to Jared Leto's take, think he can pull it off, but I'm not crazily hyped over it like I was going into TDK. And while part of that is due to my skepticism on the DCCU, a far bigger part of it has to do with Heath and the impression he left on me.
Hello, Shikamaru.
How do you feel about having a new Batman? I mean, beyond having Affleck in the role, how do you feel about replacing Christian Bale.
The way I understand it, The Razzies nominations are not about how awful the performance was per se, but a combination of that and how "fun" it would be to nominate a certain actor / actress. I'm sure there were worse performances in mainstream movies during that period, but because of the Tom Cruise backlash, they decided to nominate Holmes. Just a theory of course.
Howdy, I Am The Knight.
Batman Begins was a bad choice for Holmes. I mean, the cast was really solid and talented, so she stood out as the weak link even more. I have to admit her presence was irritating to me. She didn't look or feel an emotionally mature woman. Did she attend to get her award, btw? I've heard some actors do. :P
Cheers.
Not only that, he's not debuting in a Batman movie.
Hi, shauner111.
Now I come to think of it... not only that... the new Batman is not debuting in a Batman movie. *mind blows*
See you.