Three wickets in just three balls was enough in the end and that's what the New Zealand players did. But if the last wicket Washington was not aggressive and could throw a few overs with strikes, then there might have been some chance of victory. But there too, Washington failed. Basically, it was written in India's fate that India would be whitewashed, that's why India could not beat the target of 147 runs.
I understand your point of view that only if India could have scored 25 more runs, they would not had to face the defeat. But then we can't blame Washington Sundar or Ravichandran Ashwin for not completing the game. These runs should have been scored by the Indian top order and if they failed, we cannot just put all the responsibility on bowlers to do the batting as well.
Also i think that even if the Indian team would have won this match but by losing 8 or 9 wickets, i would not call it a healthy win. Another think that India will be playing a test series against Australia from 22 of this month. Not much time is left in this series and they need to improve this batting.
This was a tough pitch to score. This pitch was getting more tough innings after innings. New Zealand were ahead to won the toss.Though India played well there 1st innings. Subman were close to the century and Pant scored 60 as well. They have totally failed to their 2nd innings. New Zealand were not scored big on thier second innings but the batsman were failed to reach the goal. However New Zealand really played throughout the series and finally they won last and final match as well and Indian tested whitewash. As much as i know India will have a test series against Australia after this series. They must need to improve their batting side to win there. I hope they will get a lesson from here and will play better cricket on next series.