It is very difficult to win elections only on the plank of development. There are so many examples of this, Chandrababu Naidu in AP, S M Krishna at Karnataka, Digvijay Singh in MP (all as claimed by the media).
So in a way Modi has to thank Sonia Gandhi for starting the emotional issue with the "Merchants of death" comment. This gave Modi the needed excuse to revert back to emotional issues.
It is another matter that the Congressmen do not have the guts to accept openly that Sonia and the PM actually did more harm than help in their campaigns in Gujarat.
It is good for the people of Gujarat that Modi is back and there will be continuity of his policies.
