First of all, we're all here to help. I get defensive about characters with a set persona, and while I commend people trying to reinterpret the character, I don't want to just sit aside and let someone do something totally out of character with the costume. I still stand by the opinion that Mr. J would never be caught in a hoodie, unless it was laundry day. Even then, he'd probably do laundry naked. If you don't like the negativity, go to cosplay.com with your idea. You're going to get mixed reactions with this concept, and honestly, most people agree that hoodies are the wrong way to go.
Again, I apologize for the negativity, but we're here for accuracy and quality. You might have a great hoodie design. Hell, I'd buy one for myself if you offered. As soon as you tell people it's a Joker costume, their enthusiasm will go away. Same thing happened with my first attempt at a Harley Quinn redesign. They sneered and walked away without saying a word.
On the other hand, he did make an ICP reference in one of the Harley Quinn comics. "Run along, now, you insane clown posse you!" While he may respect the psychopathic clown persona ICP developed, I don't think he'd promote the juggalo fashion.
There's my two cents on the ICP/Joker relationship.
Now, honestly, when I think of "Modern Joker" I think of some sort of modern style suit, or maybe he would take a hint from the 11th Doctor and couple jeans with a suit jacket and a bowtie.
Wow. I suck at writing "quick replies" ... Sorry for wall of text, people.