Yes, absolutely. They are southerners and wanted me to learn it so they would speak in that whenever they talked to me and expected me to do the same in response. I know at least few people who do that sort of thing with their kids, if they want them to learn their language. It seems to work rather well.

well, what do you mean by 'non-Hindi-speaking regions'? Places where it isn't the dominant language? In that case, usually Hindi is the back-up language of choice before English, at least when speaking to people over, say 35. Under that, you might see more people using English secondarily. But in general, people will give you a snobbish look if you talk to them in English instead of either the local language or Hindi
Plus... just because English is a national language doesn't mean people are actually any good at it Don't get me wrong, many can speak English quite well, however, that is usually because they are speaking it quite often. The average person does not.