I need to add a comment. We got to remember this is just a comic. I don't mean to sound condescending, but super-heroe comics follow certain rules. One of which is, keep the world as close to reality as possible. That is, you just accept that somethings that should happen if you follow them to their logical conclusion, don't happen because it would change too much.
For example, Reed, Tony, Hank Pym and McCoy would have probably cured cancer and eliminated America's need of foreign oil, especially considering how much alien tech they have access to. But they don't; because it would change too much.
Yeah sometimes you will tell a story touching on these "changing the world" storylines, but they really don't change anything. So while Wakanda would change the face of Africa if it was in the real world, in the comic world it would be doomed to fail if it tried to change things.
So really within the rules that Marvel and DC play by; Wakanda really couldn't do anything then or now. If they tried, writers would have to write reasons why they failed; because if they suceeded then Marvel's America would look nothing like it does now and that doesnt work. The better way is what Reggie suggested, why they shouldn't try. After all, creating a backstory where Wakanda failed to stop the European nations, doesn't enhance their reputation for power.