Great reply... I'm with you on most of what you say.
I have a DD who is 13 now and have sailed DCL since she was 4. Our first cruise we were assigned late dining, our second 1st, and since, all late. why? because we sometimes booked late. So yeah, first come first serve. I'm a rules are rules guy. I follow them and expect everyone else to follow them as well, otherwise society would be chaos.
I've put requests to be moved on every cruise and most have been granted either by email or onboard.
I would much rather get early dining bc I HATE eating late... 7 PM is the latest I would eat anything bc I can't sleep with a full stomach and sleep is my only recreational drug of choice. It has an effect on me akin to real drugs to those who consume them. Yes, its that important to me. The times where we couldn't be moved to ED, I barely touch the food. But I wouldn't stop cruising if assigned late dining. I just live with it.
To the OP:
I suggest you take a page from Andy Dufresne in Shawshank Redemption: you know, that scene where he mails politicians every day to get funds for his prison library?
Don't do it every day, but do what I do:
Email DCL every week asking about your request to be moved to main dining right after you PIF.
I do this every cruise.
I was just moved a week ago. It took me 10 weeks, so 10 emails hounding them, plus a few phone calls.
Be persistent and you will eventually get moved.
If you don't get moved, go to the dining desk (usually in one of the lounges) right after you embark.... we've been moved there the 3 times our request wasn't granted by email.
Back to Andy Dufresne again: "Remember, hope is a good thing, maybe the best of things, and no good thing ever dies"
Happy cruisin'