My kitchen (gas cooker) has a vent that leads directly outside and man do you know about it in colder weather. However on balance I'd still rather have it cause I know, should there be a small leak, it would play a part in keeping me safer, that's my theory anyway. Having said that, although I wouldn't condone it, I can understand why folk who like it cosy would be tempted to block these vents up to stop the drafts.
