This is about context and political intelligence. Romney is speaking to the NAACP, a room full of staunch supporters of a historic President. This man is an important symbol to them and black Americans generally. Romney has been invited to address them as the GOP nominee. Further, by proxy, he is talking to black America. Blacks will listen to Romney's remarks at this convention and regard everything in it as indicative of his posture towards them and their issues, whether they like the NAACP or not. He's speaking to a black audience. In theory, he's there to try to win their vote, persuade them that that the GOP approach is the right one.
In this context, using the term "Obamacare" to refer to the health care legislation is inflammatory and guaranteed to get the bad reaction it got. Its a pejorative term coined by the GOP as a quick attack shorthand phrase, a term that turns the name of a President held in high esteem by Romney's audience and by black America in general into an epithet angrily spewed by conservatives around the country every day. And you should be clear, Obama's not held in high esteem so much because he's such an awesome president, but because achieving the Presidency was an extraordinary feat, something most blacks (including me) did not expect to see in our lifetimes, perhaps not even our children's lifetimes.
When you say "Obamacare", its denigrating the person who accomplished this singular achievement. Saying "Obamacare" does not enlighten or tell anyone anything about why the law is bad, its just a shorthand way of saying you don't like it, and you dislike the president, nothing more.
Instead of the typical platitudes, Romney would have been well served to deliver a mini lecture Clinton style on 4 or 5 points of why the policy is wrong for black America. Once he said "Obamacare" people stop hearing his argument because they are being offended by his method of delivering it. It's kinda like the reaction you might have if I fed you a delicious filet mignon on a dirty garbage lid.
Instead of using that term, he could have referred to it by its name or in any number of ways that would have kept people listening to him instead of booing him for pejoratively talking about the guy they support.
The GOP electorate sadly, love this kind of stuff. The rank and file think its cool when Newt says he would go to the NAACP convention and tell them Obama was the "food stamp" president. It plays to obvious stereotypes and it would offend a black audience, but the rank and file generally don't care. Why would you take such an approach with an audience you claim to be trying to persuade to your point of view?
Somehow, people in the GOP have come to this view that if we are addressing a black audience, we should use rhetoric we know will offend them or be inflammatory in some way, because it proves...what? I don't know. This approach makes liars of conservatives talking to black audiences, who claim to want to share their views and get their vote, but instead use rhetoric you know will be inflammatory. Why? Because it plays with the folks who's votes Romney is actually trying to get. GOP voters cheer him on when he goes to a black audience and is inflammatory in some way. They think its "principled" and "truth telling" when he rhetorically pokes a black audience in the eye for no good reason. But it makes liars out of conservatives to claim they want to politically engage with blacks when they behave in this way. Because you don't intentionally offend or inflame people with your words who's support you claim to want.
I want Romney to be effective and make his case. It's dumb and ineffective to make his case using this terminology to this audience. At a Tea Party rally, sure, they will eat it up, but this audience, no. That's just smart politics, being a smart communicator. When I say this to people, they claim they don't understand it. Check my twitter feed for the conversations I've been having and see for yourself.
It was a black audience, but that does not make his error a racial issue. I'm talking about effective communication. Simple stuff. Want to persuade this group to your POV? Avoid using rhetoric that pisses them off and makes them stop listening carefully to what you have to say. That's not a rocket science idea.