India's problem with terrorism is probably there reason.
But if I was you, I would focus more on why the other 180+ did not recognize them.
What Afghanistan has to do with instability and security related problems in India?
So in your opinion, recognition of Talibans by other countries was far more important than the majority approval, they enjoyed on the internal front on assumption of power.
By that logic, the existing Afghan Govt is better than Talibans, which has recognition by the West, despite the fact, it doesn't exsercise any authority outside Kabul and has miserably failed in tackling internal security and resurgence of Talibans.