THIS!!! It's the trade off fans need to accept and not freak-out over. The higher profile your characters rises, the more you need to learn to "grin-and-bare-it." It's true of all characters. If we don't, very quickly writers will get tired of having to deal with fans over every little thing. I'd rather T'Challa and Wakanda play a bigger role in the MU (across all books). And I accept the "flip-side" of such awesomeness is T'challa and Wakanda won't always be used right or always come out on top. It happens, it happens to all character. T'challa contained in his own little verse is fine, but it won't guarantee we'll always have him around.
It's a difficult one, I get the pros and cons of both, and (for me personally) I choose "the whole MU". I'd rather American Panther Kasper Cole showed up in Waid's Daredevil than not be used at all. I'd rather the origins of Vibranium get explored in Captain Marvel than not explored at all. I'd rather a former Black Panther Wakandan Queen has her story told in Storm's solo than never at all. As long as it's a good story, it doesn't both me who does it, or what "verse" said comic writer is in at the time.
That said... I get why some only want T'Challa used by a BP writer. I feel the same about Wiccan. I DON'T want him a main character in an event, I DON'T want him on a main Avengers team. As long as he's in Young Avengers he's safe, and he'll remain with Hulkling, his character will remain good and powerful and aweomse and he'll remain alive. But I accept the trade off is = sometimes I can go over a year without any Wiccan in any comics; and his reappearance is NEVER guaranteed. If that makes sense?