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.
I think TB's statement is selective memory on his part, but that's my opinion. I also don't know what Atlantis or Attilan followers felt about the changes, if any were made, to the status quo of these kingdoms. Being undefeated was not a part of their make-up, however, as even Asgard had been sacked before. Not so with Wakanda. Namor and Black Bolt had been deposed before, not so with T'Challa. What's next, kill-off the Panther God?
Yes, I know T'Challa will be back in the suit, and Wakanda will be on top again, but then, what was the point of it all? Mate, I miss Priest. Through all of his changes, (and I sure as hell didn't agree with that aneurysm!) he was a solid writer and gave me something to look forward to, rather than something to wait on