Its lame because it makes it so anybody can become the Joker. If The Joker is just "a guy who seems a little nutty, commits crimes, and wears makeup", then who's to say that #2 in his gang doesn't just follow suit when he's dead? Joker's always been someone that can't be topped, isn't a follower, isn't a normal person, and isn't just "some loon with some face paint".
I keep seeing the comparisons to the way Penguin was in Batman Returns, and its a good point. Look at what we have:
Penguin's distinguishable character traits:
Fat
Pointy nose
Uses umbrellas
Businessman
Wears a tuxedo usually
Batman Returns:
Fat - check
pointy nose - check
Umbrellas - check
Tuxedo - enough that you can check it
Businessman? = crazed deformed sewer dwelling penguin & circusfolk gang controller searching for parents, running for mayor, and having black blood
^ Enough that the character is turned upside down aside from appearance, right?
Now let's look at the Joker's distinguishable character traits:
Green hair - check...possibly
Purple "costume" - check
Acid flower - No.
Permanent smile - possibly, though I can't even notice the "cut smile" at all because of the makeup, and even so, it doesn't look like a smile, so if I had to say yes or no, I'd say no.
White skin - Not a yes, and not a no.
Lanky build - no
Pointy facial features - no
No facial makeup - No
No dark circles around his eyes - no
Not considered a Texan - no
Has no name - Yes, from what I've seen
Sadistic killer that uses gags and chemicals to make people die smiling - not sure yet, but it seems to me like he'll just be painting that big red "smile" on people that he kills rather than making them smile from a toxin
^ Enough that you have SOME...not all...of the physical details so if you asked people "which Batman villain is this supposed to be?" they'd replied "the Joker", but it definitely doesn't follow suit.
The thing that is annoying me, and from what I've been extracting from discussions with other fans that are displeased, is that we aren't upset that its not 100% like the comic or animated series, we're upset because details that make the character who he is are changed and for no reason. Chemicals DO bleach the skin, so why make him just wear makeup? That makes him, as the post above says, lame and simple, and against character. Would you like it if Harvey Dent just wore a Phantom of the Opera mask on the one side and claimed that was his "second face" because that's easier than him being scarred? That's basically what this Joker is in comparison. What about if Bane was just a big guy that never used any type of steroid, or if Killer Croc was a man in a cheap crocodile Halloween costume just because that'd be more common?
Change can be a great thing in a movie (ala the costumes in X-Men as opposed to yellow and blue tights) but changing a SIMPLE classic character just for the sake of change? Not a fan of it. Right now, if you threw a bucket of water on this Joker's face, he'd be nothing more than a laughing thug with long hair, and that's not the Joker that has the legacy that they need to do justice.