The live user counter is more for users to see that they're not browsing alone, to inspire moar posts. It's quite common on Japanese BBSes and imageboards, including Futaba, Momizou, most Ayashii World boards, etc.

That said, I think it's generally healthy to keep an eye on population size (which we've done since the early days, see: graph anon, news posts, etc.) - similar to how a person trying to lose/gain weight is wise to monitor their daily calorie intake. Or maybe teh sandwich is just making me think of food...