The whole point of Insightful Strike is to give swashbucklers good damage without having to have high Strength (and it failed, because you still need Power Attack). It just doesn't seem to serve much of a purpose, mechanics-wise or fluff-wise, when you have things like Ruby Nightmare Blade, Death from Above, and Greater Insightful Strike to do your damage for you. The various Concentration to damage maneuvers should take the role of Insightful Strike well enough, I'd imagine, and one of them is even called Insightful Strike!