While the Affordable Care Act is a very polarizing law in the United States if the Government was to educate the people about how covering certain conditions could greatly improve some ones life when they had no access to this type of care before the act was passed could humanize the law in some peoples eye and give them a more favorable look towards the act.
The biggest argument against the Affordable Care Act is that it requires all individuals to purchase insurance, which is clearly a boon for insurers, but they take on significant risk as they cannot exclude anyone from coverage and they cannot impose yearly or lifetime maximum expenditures. Tay-Sachs is a crippling disease that is not simple nor cheap to manage, and would be a the exact sort of pre-existing condition that would make any insurer run away. Instead they can no longer do that, they must provide coverage, and we as a society are better for it.
Obamacare's decreased public support can not be fixed with one single issue. The nationalization of 1/6th of the nations economy is something that doesn't sit well with a part of the population itself, combine that with bureaucratic failures at it's launch, and Obamacare will need to do considerable more then fix one issue if it is to improve if perception.
In the end for Obamacare to stand it chance it will require considerable change in the way the law is written, how it is run, and how it affects the lives of the people.
Obamacare has a lot more problems going for it than it can count. Being able to cover one particular disease is not going to change the public's perception of the health plan. A lot of people are angry that some of them are not going to be able to keep their previous health plan because of it.
Unfortunately, guarantees of treatment for specific illnesses or diseases will not bolster public feelings toward Obamacare. The complexities and fundamental issues surrounding the Affordable Health Care Act have done far too much damage to public perception for any such value added service to turn the tide. Open and honest talk, bipartisan agreements and effective plans for moving ahead are the most important considerations to salvage public trust and support. Offering an extra-thin slice of cake to an empty plate will barely satisfy most people.