Imagine what kudos Hilton could gain by having an inexpensive stuffed pad it could insert between the two doors in connecting rooms where the connection is not wanted. And how easy it would be to remove the same if adjacent rooms were sold as connected - Housekeeping or Maintenance could trundle it away and Bob's your uncle.
I've had too many connecting rooms - my last submitted me to a giggling, loudmouthed couple who listened to television, made loud telephone calls, and spoke loudly to each other in a Hampton Inn.
I do take earplugs with me, but I should not have to wear earplugs.