That's what the Pakistanis want to think, that where ever they go, some preferential treatment is waiting for them round the corner. Well, it's time to get out of the bed, stop day-dreaming and see the World the way it is.
Two things :
1. Nobody is waiting for Pakistanis to give them a candy. What is the benefit in that ? What does Iran or Afghanistan get in return for doing a bidding for the Pakistanis ? Just heartful of love ? Sorry, this is country-to-country relations we are talking about and not person-to-person. So, a heartful of love just doesn't cut the cake. There has to be something more than that which India has to offer and Pakistan.
India is doing perfectly fine in Afghanistan. What's wrong ? Change of government does not mean a thing. India was helping the Afghans with infrastructure, training, healthcare and finances and nothing has changed from that aspect.
There was a time when Iran used to help Pakistan against India. That time is long gone. India now happens to be in a unique situation where it has trade relations with both Saudi Arabia and Iran, with Pakistan nowhere in the picture.
2. Why would India want to bypass Pakistan ?
Now, a land route access to Afghanistan via Pakistan and thereby to Central Asia would be a good-to-have option indeed. But the route will be controlled by Pakistan. It's hard to do business with them as they don't have cordial relations with India and they mostly let their emotions decide for them.
Now, if, for some reason, they just happen to block a transit of goods, it would translate into severe loss, which will happen.
The terrorist problem in Pakistan does not really help. A proposed transit road through Pakistan will essentially go through areas in Pakistan where people are in armed rebellion against Pakistan. Of course I would not want to send my goods through that route.
It is any day better to have a costlier option, but one that I can rely upon, rather than a cheaper solution which can go wrong in so many ways! And when it comes to the Chabahar port option, the cost isn't much actually. It may actually work out to be as cheap as the land-route too.