You're assuming the information was there to be read at that time. I don't know if that is the case. It might have been, but it might have also been that insurers were waiting to see how the Supreme Court case would work out and how the states would address their issues and any number of other things before settling on a price.
I think they should have rolled it out as an "invitation only" service like gmail. Do that for about a month to work out the more egregious problems and then open the floodgates. That is hard to do with a piece of legislation, especially in the current political environment.
After the fact it's always obvious what should have been done. Oddly enough, it's always a different thing with each failure or accident. Things never seem to go perfectly, with even the most carefully planned projects.
Not knowing much about it, this seems like a pretty run-of-the-mill project management failure. The same kind that afflicts nearly every private enterprise (Google, Apple, Microsoft, Facebook, Amazon, IBM) you can name.