You're coming to some pretty game altering conclusions without really trying the changes out. Tempest III was already giving an extra attack before they normalized the attack rates. Nothing has really changed except that Tempest III comes up every 4 hits instead of every 5.
Don't try to figure out the metagaming implications with pure theory. It often leads to over-adjusting to game changes and developing less than optimal strategies. TWF benefits standing still now... so start out with trying to stand still. Don't over invest in ideas like tumbling, stunning blow, paralyzers in the like... just start with standing still.