GM sells us the basic car -- but it is up to us to make it all it can be! Let's face it, GM is in business to make money. GM is not going to spend millions on primo parts for our cars if lesser parts will suffice. In addition GM needs as large a market as possible -- some people may not want the somewhat stiffer ride of a performance optimized suspension, the louder bark of a free flowing exhaust, the rougher idle of a peekier cam, or the more cluttered ( and often tacky ) look of appearance "enhancements" or mods.
GM simply wants to sell a lot of cars for the most money with the least investment ( don't believe this -- ask any stockholder! ). GM did not spend the extra money it would have cost for; better wheels, better shocks, lighter slotted brake rotors, forged steel crankshaft, forged pistons, better valvetrain, headers and exhaust, beefier tranny and converter, greater selection of stock gear ratios, etc., etc., etc.
While a stock Corvette is a nice sports car, there is a huge difference between a stock Corvette and one with some well chosen performance modifications! It just depends on what you want -- or have the money to do. I have always felt that a Corvette of any year could be made better -- even classic Corvettes look, run, and handle better with the period mods which were popular at the time. ( Just say no to the "appearance" mods though, PLEASE. I don't know anyone who likes the look of a new or old Corvette with a bunch of tacky junk glued to the interior or exterior! In modifying a car the idea is to replace, or modify, stock parts with better made and performing parts. Just my not so humble, but correct, opinion!! )