I see what you're saying, I just think if it was done appropriately it wouldn't be insulting.
Whether we like it or not, there's not much to provide in terms of Africa that wouldn't be better placed inside Animal Kingdom.
Why not have a huge land based off of Rwanda (Wakanda is rumored to be nearby), then include Wakanda behind it. It wouldn't dilute anything if it was contained to it's own area, similar to London & Diagon Alley.
Of course we're talking about Epcot today. If Mary Poppins can have a made-up street in the UK & Norway is able to contain made-up country based off it, I don't see why Africa cannot be represented in all of it's glory while accompanied by a made-up Wakanda. RAT is literally the only one that gets away with this because it actually takes place in a real city. Poppin's, Frozen, & Wakanda are all in the same boat.