"Traditional" in this sense means "fixed seating." The traditional dining room has the same dress code as the other dining rooms and is NOT more formal. Yes, guests have the same table and wait staff every night. That means there is no standing around waiting to be seated and thus, no queue. It is possible to get a table for two for the duration of the cruise and that would mean no fellow passengers as tablemates every night. This is not some new-fangled idea dreamed up by Princess: this is the way dining has been for decades on nearly all cruise lines. (Hence the word "traditional.") This new dining scheme makes it possible for cruisers who like fixed dining (and there are more of us than you might think) to get what they want by allowing other diners to be more flexible in their dining choices. Princess is giving you a choice.
For those of you who "disapprove" of the new approach, consider that all those people in traditional dining are not standing in the queue with you waiting for a table, nor are they grabbing all the desirable tables in the reservations dining room before you can get to them. Win win.