Eat using hands

Fork usage primarily came from Italy where eating hot pasta with bare hands was a problem. During the Renaissance, Italian culture became the in trend thing and the table manners of eating with fork & knife spread elsewhere. Fork & knife, make real sense when you have bulk meat that you want to cut. Also, when the foodstuffs are little more homogenized, these devices work better.
The kind of food you eat decides the kind of utensils you use. There is no one size fits all. If it is a burger or a sandwich, you better eat it with bare hands :).

Indian foods are so diverse in form and structure that no group of metallic devices would really do the complete job. You need to use all the dexterity of your fingers to manage the food. It is not without reason that we are given opposing thumbs ;-) [The papad in the center of the plate has to be broken (like Tortilla chips) and fork would not work in this case.]

Here is Dosa - one of the southern delicacies. It is 10 times thinner than a pancake and has to be eaten with sauces of different densities. You need a superhuman effort to use a fork to eat this.

Many of the Indian foods come stuffed. Here is Vada pav (a sort of burger equivalent). Would you eat a burger without bare hands?

In short, there are liquids, semisolids, powders, stuffed food, extremely thin layers and so on in our cuisine. A combination of this is too much to handle for a knife & fork.

Another traditional aspect is the usage of banana leaves as the plate. In many parts of India, banana leaves are used as plates (India: Why is traditional food served on a banana leaf in the states of South India?). The leaf makes it even harder to use a metallic device as you could accidentally cut open your plate & mess up the table.

Ok. I'm hungry now and gotta go.