Nono, Zoidberg has 3 phases. One is cheap slapstick comedy, like screaming at Fry's ex-girlfriend in They Cryonic Woman, or squirting ink 3 times in an episode. That's usually really bad and I hate to see Zoidy treated that way.
Sometimes he's alien and uninformed but still confident, usually in his doctor role. This is good.
Sometimes he's pathetic and lonely and sad, which I don't like to see in excess. But it's nice to see him excited over an Xmas card or when he gets a pogo stick from the demonic Santa (One of my favorites. "You've all been VERY naughty! Except for you, Zoidberg. This is for you."
You couldn't have any other character eat bait and get chased around with a fishing pole, or suck on the professor's head. And I'm still holding out to see him eat Nibbler.