Donglang is important to India for two reasons, because it overlooks the Chicken's Neck corridor, and because it was a chance to show that India would uphold their mutual defence treaty with Bhutan.
India's position was originally to protect Bhutan, after they failed that, their position was "No more roads in Donglang".
Now they had to change their position again.
And once the next road is built, they will have to change their position again. India can never lose, not when they keep changing the goal posts.
But ask anyone who is not Indian, what do they think of the massive military and infrastructure buildup in Donglang? Why did India fail to uphold their mutual defence treaty with Bhutan?