unfortunately the reason is simply to put a woman on Money...
If it were because she was strong, defended the constitution and/or was otherwise epic few would Blink... but no...
she moved to the short List because she was Female, and to the top of that List because she was Black
and the Only reason why she's replacing Jackson on the 20 rather than Hamilton on the 10, is because the F'n Play... I'd rather she be honored because it is the Correct thing to do, and Not the Politically Correct thing right now