I think it is more than simply getting rid of Obamacare. There are about 100 reasons why, but our health care system needs some work. For one, **** is way too expensive. People shouldn't be paying $32.50 for one aspirin in the hospital when you can get a whole bottle of aspirin at Wal-Mart for 3 or 4 bucks. Republicans have come out with some ideas in the past, but getting more than 30% to agree on any of it is a problem. Everyone has their own idea, and they seem unable or unwilling to get everyone in a room where this stuff can be hammered to where they can put a plan forward for a vote.
And to a lot of voters, not sure if it is a majority, but to a lot of voters, health care and health insurance is the most important issue they face. Democrats are at least attempting to address the issue, no matter how wrong or misguided folks might feel those attempts are. Republicans talk about fixing health care, but the only thing they have done is destroy the ACA. Doesn't matter if it is a **** law or not. All voters see is that they destroyed it and have offered nothing to replace it. Democrats are yapping about Medicare for all, which is probably more costly than the ACA, and I think people are aware of that. That said, they would rather have SOMETHING even if it is going to cost them more. I know a lot of people think optics are unimportant, but it matters to people that don't see you advocating for their well being.
Republicans have failed in that regard. They keep saying, "Well, vote for me and I will get something done, trust me." After that, they rarely address it. If Trump loses in 2020 and Republicans lose the senate, healthcare will be a big reason, if not THE reason why.