I’ve never looked at Dogen, or if I have, I don’t remember doing so.
What I do know is that, in my experience, there is a huge difference in how people interact with you when they don’t think you can handle the complexity of what they might say. The most extreme version of this, of course, is when people yell words at you while flailing their arms, in the hopes that higher volume will suddenly endow you with divine translation abilities. And the way that a lot of people judge whether they need to gesticulate violently at you is through your accent.
I’ve noticed that accent is even used at times as a proxy for intelligence: if you sound like you’re “not smart” people will treat you that way. If conversely you sound native, people are far more comfortable with getting to the substantive content rather than worrying about the transmission of the content. And they are also far more forgiving of small errors because they are willing to assume it’s due to a carefully deliberated choice of words to show a certain nuance rather than an outright mistake. This has been my experience wrt to English (as a native observing interactions between natives and non-natives), French (same), Spanish, and a couple more languages.
Being able to hold deep conversations of the quality I’ve noticed natives hold amongst themselves is the main reason I would place a lot of emphasis on pronunciation and pitch.
Obviously, people will have equally anecdotal counter-examples, but having been on the butt end of such interactions even once was enough for me to realize that accent is critically important if you want to be taken seriously by more people than otherwise would have paid attention to the content of your speech.
As for the argument about starting out with accent and pitch: absolutely agree it’s a good idea for any language. Bad habits are very hard to fix. Might as well get a head start.
As someone who has fought the battle early in his childhood to not let his accent get influenced by his environment, I can assure you that the way I am perceived when I speak is very different to the way other English speakers who have been influenced by my (typically non-English-speaking) environment are perceived. Same for French, to an even larger degree.
@Jonapedia, I suspect, will have some good insights on this front too.