While I can agree to an extent on what you're saying here, the component that's lacking for me is actual consistent publishing. Asgard has been shown in Thor uninterrupted for years. Atlantis and Attilan benefit from exposure through the FF, not so much Wakanda. The Black Panther books are not published for more than a few years at a time, then are cancelled, and then there's a new take or whatever.
I accepted Priest's run because there was finally more development of the character and Wakanda, but in all actuality, what is it to say that a country has never been defeated, when this fact wasn't truly a part of their lore until Priest's run? When Hudlin came one, the undefeated aspect took precedence and is now gone.
Tom Brevoort recently pointed out that the Black Panther has been published in one volume or another pretty consistently for most the last ten years -- which is certainly more consistent than Namor or the Inhumans have -- so Wakanda has been exposed to readers much moreso than Atlantis and Attilan have during that time period. Namor hasn't had an ongoing present-day title (until recently) in decades and neither have the Inhumans.