Sony has suffered more than they anticipated at the hands of the hackers and rather have more issues to deal with, are trying to clear up what the hack has already caused. It's one film versus the future of the company, so they had to look at the bigger picture. They could still be hacked again, so there is no guarantee they are safe yet.
I don't think they should have pulled it, I was actually looking forward to seeing the movie. If they really were being threatened and things like that, I do understand why they would. They had two awesome actors in the movie and it looked like it was going to be pretty funny.
"The Interview" a movie starring Seth Rogan and James Franco was recently pulled from theatres around the country. Sony was attacked by cyberhackers that threatened violence and financial harm. Due to increasing pressure they were forced to pull the movie. The pressure obviously derived from the North Korean government and they should not have influence in the sphere of the United States.
Sony have caved into peer pressure here and as a large company many people are disappointed by their actions. They should not have pulled the film at all as they are leaders in free speech yet they have gone against what they believe in and have let their consumers and fans down.