New arenas are so quite, because it makes for better concert acoustics.
The new MTS centre in Winnipeg contains acoustic paneling which eliminates the echoing effect plagged by many older arenas. Its concert quality is compared to the concert hall, which is very high for a sports venue.
The old Winnipeg arena was one of the loudest arenas in the NHL, second only to the old Chicago arena, due to its concrete walls and large right angled corners within the seating area. Massive echoing!! It made for a great hockey atmosphere, but very bad concert venue.