I don't agree that one should be excluded from being a hero if the task undertaken was part of one's job.
The emergency service personnel on 9/11 who lost their lives are regarded as heroes but they were just doing their job also.
I'll admit having too many heroes would result in diluting the status however that doesn't mean we should be overly harsh in denying hero status where an extraordinary feat has occured during the line of duty.
As a trainee pilot I recognise how many factors were involved in bringing down a heavy, speeding chunk of metal safely to rest in water and they are immense. The amount of energy involved boggles the mind and even the slightest of errors could be catastrophic. Maintaing the right angle of attack with no engines thus little or no hydraulic power, maintaining composure knowing that one mistake and lots of people including yourself are going to die horrendously, thinking about your wife and kids getting the news of your death, seeing the water approaching rapidly knowing you only have one shot, is more than just skill - that's a gift!
People should recognise that not every pilot could have achieved what Sullenberger achieved and that there is a large percentage of pilots out there that don't practise hand flying but instead leave the computer to do it all and only do what they need to pass the 6 monthly check rides. The outcome with one of these pilots in charge would have been very, very different.
With this in mind, is Sullenberger a hero? I think the passengers will agree that he is.