Just as Romneycare is under attack, along comes more evidence of its success - this time, in helping to create more affordable coverage plans. The cost savings is important because both “Romneycare’’ and its famous offspring, President Obama’s health-care overhaul, were branded mainly as ways to decrease the number of uninsured people, partly through the much-demonized requirement that individuals who can afford insurance must buy it, and, in the case of Romneycare, a mandate on most employers.