I agree we'd be better off with a public insurance option. But the only viable solution to the "health care crisis" seemingly doesn't have enough support in Congress. See: Blue Dogs.
The argument against suggests competition between health insurance providers creates more affordable, better insurance. And providing a public option will effectively kill competition, since private insurance providers could not compete. But nobody would be arguing for a public insurance option if competition actually created better insurance.
Having changed employers twice in the past six months, I have taken a look at different insurance options. Personally, I didn't see much in the way of choice, at most about two providers. Most places, there is no choice, thus no competition at least at the individual level. And if you had a pre-existing condition, the provider could simply decide not to cover your condition, unless you had proved you had prior coverage. (Or maybe not at all for some conditions. I didn't check the fine print. Woe is the worker who has a chronic illness and changes jobs frequently.)
I'm speculating, and perhaps Intrade traders may agree, that the public option will fail. Congress will devise some weakly formulated regulations, which might result in crocodile tears and exagerrated protest from private insurance providers. And any marginal improvement should get some public support. Obama will have little choice but to go along for now. And that will be that.