It is "needed" to maximize all the perks the haven has to offer and having that level of knowledge of the ship / ports to help with your bookings is invaluable. Is it necessary to enjoy your cruise? Obviously not. But it is a service provided to Haven bookings and you can definitely notice the difference between a good concierge and a bad concierge when you utilize one so it can make your cruise that much over the top if you have one of the best (which they usually put on the newer ships).