The Corvette averaged 14,229 annual U.S. sales from 2009 to 2013.
The average age of a Corvette owner is 59 years old.
The current base price of a new Corvette is about $52,000
The Ford Mustang averaged 74,192 annual U.S. sales from 2009 to 2013.
The average age of a Mustang owner is 51 years old.
The base price of a Mustang is about $22,500.
Attracting new young buyers is important, because their lifespan as repeat customers is longer. Having a lower priced base model is likely to produce more new buyers, than a higher base price would. The Ford Mustang already generates much more revenue than the Corvette does, therefore it does not need to compete with the Corvette.
Since the 2010 model Chevy Camaro debuted in 2009, the Camaro has averaged 79,231 annual U.S. sales from 2009 to 2013.
The Camaro also has a much lower base price and a younger sales demographic than the Corvette does. Therefore, in terms of sports or sporty cars, the Camaro is a far greater competitor to the Mustang than the Corvette is.
The Corvette currently offers Chevy, name brand recognition, not big sales figures. The Mustang offers Ford both name brand recognition and substantial market share
I think a better question would be, why does Chevy keep producing a sports/muscle car like the Corvette, for old guys, when the Camaro sells roughly 5.6 times as many units and attracts younger buyers?