There have been many depictions of Wakanda. It started out differently from Reginald Hudlin's utopia retcon. I think an issue if there is one is a non-Americanizsed/Western lead character along with the whole supposedly advanced Africans throwing spears and dressing in animal garbs and worshiping animal deities. It's like the whole thing with The Mandarin.
The majority of Marvel Studios movies have been set-ups(origins) and sequels to them, the only new property has been Guardians of The Galaxy. This is after six years of films(eight films in total, nine after Avengers 2). So it's not like they're going all out of their way to specifically avoid it, by burning through every other character not named "Black Panther". Obviously Doctor Strange will change that, but that's part of a slate of films that haven't all been officially revealed. A Black Panther movie could be one of them or the character could be in one of the films
.
Marvel wont suddenly rush out a Black Panther movie because Warner are making Cyborg
, vice-versa with Ms. Marvel and Wonder Woman.