Simple.
It's Modi's personality type. He is tough but has no stomach for wars. Both are very different things.
And I have had many such friends over the years, who were nationalists and were tough, even wanted to punish Porkis, but when it came to actual war and the fallout, they backed out because they got cold feet or too much empathy (ex: Abhinandan case or seeing casualties). Real war requires aggression, kind of Machiavellian characteristics (such as supreme confidence) and managing what can be various adverse fallouts, example: nuclear overhang, sanctions etc. Then comes planning.
Also, there is the election angle. One thing good in the Indira times was that, she was overconfident of the hold of Congress on the electorate and winning elections. So she was not really bothered about adverse consequences such as losing elections. BJP on the other hand is a new kid in the block and is always looking for ways to preserve that Kursi.