This post, from Reid Hoffman, is worth reading:
The basic idea is that, by coupling employment and healthcare, most people cannot afford the risk of leaving their job (even if sub-optimal) to start a company. I know that I have often done the COBRA dance before the ACA came out when starting a new company. With the ACA, people aren't tethered to their jobs, allowing them to start new companies.
This is good for entrepreneurship, which is good for businesses, which is good for America. Full stop.