Aviation safety has moved on a lot since the 70's, while it's understandable to have teething problems when introducing new technology, both the carriers and their passengers did not sign up to become Beta testers.
It has thankfully, yes. My point was the hullabaloo slowly died down and the new technology (then NiCad) moved forward. I don't think it will be any different today.
Boeing's solution wouldn't have been acceptable in 1960 let alone 2013, the more you read the report the worse it gets.
I too question the certification process. Nothing turned up. These two incidents are apparently a complete surprise to the cosmopolitan group involved - the Japanese battery manufacturer, the French electrical system integrator, Boeing, and both the American and European regulators.
Boeing didn't design the plane to have a battery fire in flight, I'm also damn certain that their calculations are way off on the battery swap frequency, if there's a problem with the battery, resolve the problem so it doesn't occur.
Truth be told, the battery's case and surrounding structure were designed with a possible overheat and fire in mind. This was mandated by the FAA. Boeing, actually Thales, France, paid an enormous amount of attention to the volatility and other dangers associated with lithium battery technology and it was thought all bases were covered. As it turns out, something got round their collective thinking.
Your point about the multiple swaps is a good one. It was not so much a longevity issue, it seems there were problems that nobody understood and since the electronics and computer wizardry were given a pass, the remaining troublemaker left standing was apparently assigned to a series of failed battery packs.
I feel fairly certain the problem surely resides within either the battery or the charging-monitoring system. What else is there?