The more varied styles you know, the better you are.
Karate is a hard style that tends to focus on straight line attacks.
judo is more soft, involving grappling and such.
If you don't have the judo and someone grapples with you, you are less knowledgeable about what to do. You'll notice some of the best fighters have taken many different styles. the weakness of one can be helped by using a style strong in it.