I think there is more than enough evidence that EA has been rushing it's many studios to push out premature games and Bioware's last two games were definitely fast tracked too much and quality of story, character, and gameplay mechanics were adversely affected. Also anyone who thought DAI was ready and treated that "first" delay as legit was pipe dreaming, I mean when was the last time Bioware's "first" release date actually panned out.
You still haven't used a non-vague reason as to why you believe the game needs yet another delay. With the reasons you have for a delay you will always be right in your own mind when the games come out because every small bug or story part you don't like can be used by you and others who have your outlook to state that the game indeed needed a delay.
Also, with your argument if the game got delayed multiple times in even smaller intervals it would meet your requirement of delaying more than just once, or actually two times. Delaying for the sake of it to give people like you a better feeling is not exactly sound advice. DAI will have had more than enough development when it comes out, close to 4 years. If the game is no good when it comes out this year, no delay would have changed anything. The quality of story, character or gameplay mechanics don't change because of a delay because the foundation of all that has been laid down at the beginning of development and if that doesn't work a delay is not going to change such a thing if a developer thinks the foundation is sound. Delays are general used to get a game ready, not to overhaul the game in the core features you just named. If you hated so much of the last two games most of those elements wouldn't have changed with a longer development cycle, except for DA2 it would have given more content and probably less repeated levels but that is really it. The gameplay mechanics of DA2 had nothing to do with the short development cycle but it was a conscious decision on the part of the developers.