So the real questionm here is whether MedicAid is worse than no insurance at all. The good folks at the Incidental Economist have a post with a dense series of links as to the complete lack of evidence for this hypothesis.
Now one could argue that it would be nice if MedicAid were better insurance, but that doesn't seem to the concern of the author of the post. Instead, it seems to be about reducing support for health care reform without really positing a superior solution.
UPDATE: It seems that the Incidental Economist addressed this twice, with another post pointing out that reimbursements under MedicAid are set to increase (and that this should increase the number of physicians willing to accept MedicAid).
UPDATE 2: Karl Smith has a rather clever point here on the same piece:
Is the suggestion here that the fixed costs associated with running an office are so high that the breakeven point is achieved from a maximum throughput of full insurance patients? And, further that there is simply no way of operating an office with lower overhead? I can see how its not profit maximizing to accept Medicaid patients. I can even see how in a perfectly competitive market providers would have bifurcate into Medicaid and non-Medicaid providers. However, I do not see why the market cannot find a way to provide paying customers with some level of service.