Those Destroyer Droids seem a lot more dangerous...

Those Destroyer Droids seem a lot more dangerous and threatening than standard issue Battle Droids, which are probably the LEAST MENACING ROBOTS IN THE ENTIRETY OF CINEMATIC HISTORY, behind WALL-E and James Franco. Why not just use Destroyers?
Look, they’re called the “Trade” Federation, not the “We Love Droids! Robots, YAY!” Federation. So they ordered several billion of the wrong model. Sheesh. Cut them some slack, Mr. Perfect.