They really need to get someone who can expand on Jaffe's design for GoW1. If not expand, then at least refine what's there...its been about 10 years. And just last week, a western team put out another action game that falls in the "it's not japanese, but it's kinda mindless fun" action game category, so it's not impossible!
but I'm guessing the sales data precludes any need for innovation, considering it hasn't changed at all, aside from graphics.