1. It's important to note that people buying insurance for themselves is a small minority of the market (employer-provided and medicare/medicaid are the big parts of the pie), so it's absurd for the architects of Obamacare or any alternative health law to penalize (edit: or threaten to penalize, without conferring coverage in exchange for the penalty... no can do, that would be the evil public option!) the exact people they need to help the most: people whose employment doesn't provide insurance, and who don't qualify for medicare/medicaid.
If you're in a large health insurance pool with people negotiating for better coverage and pricing on your behalf, and the org behind the pool is already committed to paying the pool's insurance costs, things work pretty well. That's not a healthy private health insurance market; that's an opaque, balkanized system.
2. The (increased) number of insured is commonly cited by proponents of Obamacare as the metric demonstrating success. The numbers I've seen, however, show that while yes, more people have insurance, fewer people can actually pay their medical bills if they actually have to use their insurance. I have every reason to believe that's true, due to opaque pricing, massive deductibles for most plans, and the rapidly ballooning price of even the most basic plans. How is more coverage a success when most of those newly covered people can't pay their bills?
3. The obvious: healthcare insurance costs are skyrocketing. Obamacare can't be a success if just the cost of health insurance is going to start pushing massive numbers of lower-income people out of the marketplace.
1a. A tangent from point 1: The tie between employers and health insurance must die. There's too much incentive to do things that are just awful when most larger corporations will just eat the cost of reasonably good health insurance, and tweak their business elsewhere (increase prices; decrease other employee benefits) to make up those health insurance expenses if they go up.