The Wakandans are actually really shitty people...

With just the slightest critical observation, this society is worse than any other in the world. They consider themselves better than anyone, enough so that they say allowing others to enter would "make it like everywhere else". That's literally segregation, but it's portrayed as acceptable. Also, despite keeping their community apart from the world, they have no problem crossing boarders and imposing their will in other nations. And finally, the concept of hoarding life saving technology and keeping it from the world is tantamount to being straight up evil. If a nation that acted that way existed in the real world, every country would rise up to oppose them.