Hospitality

Why do people say "you're more than welcome to join us"? more than welcome. Come on, that's overdoing it, isn't it? Let's be a little discriminatory and conserving with our words. Is it necessary to be overly nice to the point of being saccharine? Isn't saying "you're welcome to join us" enough? And second, what does "more than welcome" mean? "You'd better come or I'll wait for you inside your house with a sack full of pennies" ?