I fully agree - I'd like to see single-payer tomorrow, but that's as much of a cultural as an economic change and as you point out there are large entrenched interests in place already; the ACA is a flawed by still necessary beachhead onto that economic territory. If I thought it could all just be improved by fiat I'd be urging people to vote for Bernie Sanders, but I'm not - having a beautiful ideal is mind does not automatically provide the tools and resources required to attain that vision, a problem which seems lost on many of his supporters.