The people of Gujarat felt insulted by Sonia Gandhi's insensitive comments. Even otherwise, the results would not have been drastically different because of the development work which many Gujarati people acknowledge as significant - a view shared by many impartial Muslims of Gujarat.
Also the fact of Godhra - had there been no train coach burning, there would have been no mob retaliation. Congressmen and people like Laloo wanted to ignore the trigger while blaming Modi for the mob response. They conveniently forgot to acknowledge Modi ordered troops within a day to bring order.
Whenever Modi spoke against Terrorism (quoting Afzal Guru, Sohrabuddin as examples), Congressmen played it as anti-minority view of BJP / Modi. They probably did not realize the grave injustice they do to patriotic Muslims by colouring all of them with the same brush when they said Modi is speaking against Minorities. In fact, Modi tried to correct the Congressmen. But they were not listening to him carefully.
Congressmen goofed up in reading the public mood, and they insulted them more by their dumb speeches. Further, the public rejected opportunistic politics of people like Keshubhai Patel.
As long as Muslims do not realize the harm the so called secular parties do to their interests, and Hindus continue to feel the insults, we will see such results.