For starters, you win the presidency with 270 electoral votes. If you rank Obama’s 2008 statewide victories from biggest to smallest, and take into account the changes to the Electoral College because of the latest census, North Carolina provided the 344th electoral vote for Obama–meaning, it was just gravy. The state that put him over the top was actually Colorado, and Iowa was a close second in that regard.
So if he was looking to hold a minimum of 270 electoral votes by using 2008 results as his baseline, either of those two states would have been better than North Carolina. In fact, any other state that he won in 2008 would have been better. His margin in North Carolina was just 0.32 percent, smaller than his margin of victory even in Indiana, smaller even than his margin of victory in Nebraska’s Second Congressional District.