I just booked the 4 night Dream for May 2017 2 weeks ago. It's gone up 75.00pp since opening day. Not a big deal to me. I'm not the type person that plans vacations years in advance. I really never thought I would cruise on the Dream again, but were going to WDW, and I decided to throw in a cruise. I really have no idea what I want to do next Summer so booking and re- shopping is just a waste of time. I'm guessing that a there's a pretty good percentage of people that book on opening day that end of cancelling because they change their mind, life gets in the way, or they find better deals. I think psychologically it makes people feel good having a vacation booked even if they don't know if they're going to take it. At least that's the impression I get from visiting travel sites.
I haven't noticed this, but I don't book school breaks. I would never pay Disney prices Easter week so opening day means nothing to me. I can see why it saves you money, but those cruises would never even be a consideration for me. There are very few
DCL cruises that I think are a good price on opening day or any other day for that matter.
I find the other cruise lines to offer many of those things. I don't find clean ships, smiling employees, and great customer service to be exclusive to DCL. What I think DCL does better then anyone is cater to kids and offer a unique experience for families. I think it's obvious DCL doesn't value their repeat cruisers, but like you said they really don't need to.