1.I dont want to get into this discussion, but it is logical and courteous to answer a question in the language that it is asked in especially if you know the language properly. Why would a person who knows English ask a question in another language unless he wants the answer in that language? It is OK if your not so fluent, but in most cases they know enough to answer the questions.
2.As a person who was always given an extra edge(life saving, rank saving) by English in academics and every where else and as a person who loves English, I consider English as only a tool, and a very useful one at that, for communication between people of different regions, for bringing the world together even though it is no where near the most spoken language, and especially for us, having a good career.
3.English somehow feels "artificial" and not properly suitable for Indian emotions. English sounds funny when spoken by us due to the "Indian" expressions and modulations we add. Our expression of fear, anger, happiness etc are greatly different from native English speakers, so don't mix well with English.
4.Also with all respect I am not a supporter of new age educated parents speaking to their children only in English and making them consume only English media for 90% of the time even if they do that in the greatest interest of the children.
5.I have a lot a friends and acquaintances who have a different mother tongue and obviously we communicate in English and never have we forced them to learn our language, though they eventually learned it.