Howard really occured to me as too bad to be truly bad, particularly with how he is introduced as a very stereotypical schoolyard bully. And to be honest, I'm sort of intrigued that they put somebody so obnoxious among a bunch of otherwise fairly predictable types.
As for Chako, I suppose it's just a gut reaction to the "talking cat? ROBOT cat? Cheeky robot cat?!" line of reasoning. I was never too fond of the cute animal mascots that pop up in anime from time to time.