i'm sorry but isn't the main point of a business to make money?
these game companies are for profit of course they would sign deals with who ever has the bigger wallet.
You gotta understand that Microsoft paid basically for a service that Rockstar will provide.
That service is developing DLC for Microsoft's Xbox LIVE customers.
I'm sure if any of you were running a business and were offered to develop a product exclusively for a very large sum of money you'd take it.
And as Ash said Take 2 has had financial problems so 50 million is something they'd be stupid to pass up.