True strike is a lovely spell to use when you're ambushing someone and have a surprise round to spend on it. But, frankly, in *any* combat I've been in, wasting a round on an action like casting true strike during combat is *always* a bad move that could, in fact, lead to party deaths. The benefit is not worth the cost of wasting an action.
I'm sorry, but I think this is a case of theoretical concerns being outweighed by the realities of combat. If the goggles *always* gave you a +20 insight bonus, that would be disgusting. However, the goggles would, in fact, give you a +20 insight bonus only if you use an action for that, and only on your next attack. If you Power Attack for all 20 points, you better hope you hit with the first attack, 'cause NONE of the rest of your attacks that round will.