Some analysts have suggested the boos may help Romney by making him look magnanimous and showing that he's willing to appear before an unfriendly audience to make his pitch. It's doubtful, given Romney's reaction and the campaign's decision to send out a version of the video with the boos edited out, that getting booed was part of Romney's plan. Nevertheless, the Romney campaign is likely to use the boos to its advantage going forward. Conservative pundits, already wary of at the NAACP for previous slights, will foment outrage on his behalf. Politically, it's hard to see how the appearance hurt Romney, or how it could have—so it's overstated as an example of political valor.
There are substantive reasons why Romney's pitch fell flat. Romney told the NAACP that "I believe that if you understood who I truly am in my heart, and if it were possible to fully communicate what I believe is in the real, enduring best interest of African American families, you would vote for me for president." This is a spectacularly bad pitch for any politician, because it happens to matter very little what candidates feel in their heart. What matters is the party they represent, and the policies they've committed to pursuing.
Romney is committed to pursuing austerity and the repeal of Obamacare—neither policy is popular with African American voters. And it was Romney's pledge to repeal Obamacare that got his ass booed. The boos, of course, play into the "uppity" narrative pushed by dog-whistlin' rightwingers, so Fox News will be running the tape of Romney getting booed on a loop between now and November.