Those contracts are put out for competitive bids. Profit margins for defense contractors aren't very high. The prices are driven by a combination of strict requirements, lack of economies of scale, and legal compliance with government mandated processes.
Consolidation of defense prime contractors was inevitable due to budgetary realities and the escalating complexity of major programs. It's unlikely that keeping a bunch of small, weak companies around would have produced better results for the military or taxpayers.
