Its ok to say NO when somebody asks to take a picture. They will not force you to take a picture. Most of the the locals asking for pictures are themselves coming from villages and country side. They are just curious to see a foreigner for the first time and hence want to take a picture with you or other foreigners. In bigger cities you may not find this aspect (maybe less) due to people goign on about their busy lives and used to seeing foreigners on a regular basis. Travelling in India requires you to have an open mind as you will come across a variety of people and culture due to its breadth and size. People who want remain in their comfort zone better stay away from India, on the other hand if you want to have a true unique travel experience , better have an open mind, learn and interact with people , with a wide variety of culture, people and landscape, India offers it all. In the past, the Korean media and most Korean youtubers have been mostly focusing on negative aspects of India in a small geographical part of India(may seem big to you coming from Korea, but India is 60x the land size of Korea), hence the stereotypes of India is so much stronger among Koreans. Hopefully things will change with time and when you travel outside of the tourist traps of Delhi-Agra-Rajasthan.