BERKELEY – When historians look back on the United States’ Patient Protection and Affordable Care Act (ACA), President Barack Obama’s controversial 2010 health-care reform, we predict that they will not devote much attention to its regulations, its troubled insurance exchanges, or its website’s flawed launch. Instead, we think that they will focus on how “Obamacare” encouraged a wave of innovation that gradually tamed the spiraling costs of a dysfunctional system, even as millions of previously excluded Americans gained access to health insurance.