Actually, I played the Witch Doctor quite a bit at the BlizzCon 08 demo. He is a badass. His skills are amazing and really fun to use. Non of that effects the way he's a) old, b) hunched over and c) shaking.
If you can justify it to yourself that he's weighed down by his awesomeness and shaking because he's about to explode with power, then that's fine. However, for me, it still just doesn't sit well. Tone down the masks, tweak the character model a bit and I'm good to go.
I don't need to see what else he can do (I know his skills are badass)... his look still bothers me.
Then I guess nothing can be done to help you play it so... I guess just don't play it. Doubt they're gonna change the model, because that's how they want him to look; all crazy and creepy. So if it really bothers you and you feel like a clown while playing it, just don't play it. *shrug*
"I'll try a pagan friend, thought I, since Christian kindness has proved but hollow courtesy." - Moby Díck