It's a wonderful tree; grows where most others can't and is generous with fluffy yellow flowers and long seed pods. But, living where I do and where it does, I've never heard
Acacia used as a human name (there's a suburb called
Acacia Park near where I live) and I'm willing to believe that it's because of its long, mean and menacing thorns.
Anyone who reads
Rudyard Kipling's Just-So Stories will remember the Wait-A-Bit Thorn Tree in the story of How the Elephant Got His Trunk. That's an acacia. Its Afrikaans name translates as Hook-And-Stab, because it's got both straight and curved thorns.