He said that because people were worried that the doctor the currently had would suddenly be unavailable to them when the law kicked in. This is exactly what happened, to a lot of people. It happened to our family. The insurance policy with which we were perfectly happy evaporated because the law considered it unacceptable (the new law requires that we buy insurance that covers, among other things, maternity care ... which is super handy now that we're in our 50's). The new plans from which could choose did not include the doctor we're happy with, and precluded the use of two of the nearest (and best) hospitals. Our premiums went from roughly $250 a month to over $500, and our deductible went from $2,500 to $12,000.
Each of these things was predicted with great clarity by not only the people opposed to the law's passing, but also by the people who WROTE the law. But in front of cameras, Obama lied about each and every point of it, repeatedly, and deliberately. If he had been honest, and if he'd talked Pelosi and Reid into also being honest about the consequences of the law (instead of the "You'll have to pass it to see what's in it" explanation she provided), it would never have passed. Democrats talked into voting for it have since said they wouldn't have voted for it if they'd understood the huge new costs, taxes, and service limitations that it puts on middle class families.
You know, and Obama knew, EXACTLY what "you can keep your doctor" meant when he said it - he was trying to tamp down the very vocal concerns that exactly what has happened would in fact happen. He knew it was going to, but he lied about it anyway. What I don't understand is why you're trying to spin it for him. What do you gain by attempting to back up the deception?