Real question is why would any country be it India or any other country want to take Nepal as their state. There is a reason why British never came after Nepal. We all think its because we were 'strong ' but part of the reason is Nepal has nothing to offer .
Nobody is looking for headaches besides getting more territorial land etc was the old way that's not how countries think of power now and based on how our politicians behave Nepal is already a part of India believe it or not. As you all know nothing happens in Nepal without indian support. An ambassador of India to Nepal can summon all the ministers and prime minister whenever he she desires. All the politicians go to India for "pilgrimage". Maoists lived in India while brainwashing people about how they are against India and USA. It's all a game.