they aren't
India was chosen to host the 2010 Commonwealth Games.
they randomly got chosen
Each city wishing to submit a bid makes a 30-minute presentation to the General Assembly of the Commonwealth Games Federation, which then votes on the cities. If no city gets more than 50% of the vote, the lowest-scoring city is removed from the ballot and they vote again, until there is only one remaining.
Christchurch hosted the Commonwealth Games (then known as the British Commonwealth Games) in 1974 from January 24th to February 2.Christchurch was chosen as the host city at the Mexico City Olympics.
Because they sign in
Yes, they have to bid to host it again.
India was the host for the 2010 Commonwealth Games.
Glasgow, Scotland, was the host of the 2014 Commonwealth Games.
Glasgow will host the 2014 Commonwealth Games.
1998 Commonwealth games
The Commonwealth Games Federation decides the host of the Commonwealth Games.
India is part of the Commonwealth; a number of countries under British rule. All countries in the Commonwealth are entitled to host the Commonwealth Games. If by "should", you mean that it is seen as a rather poor country, you are wrong. India is a fairly big business capital, because lots of trade happens there. It is on par with, say, Thailand or Malaysia.