As I am sure you know, Corvette's are light and relatively inexpensive compared to many many many other performance cars out there. Sound deadening is one of the weight savings, as well as fancier liquid filled engine mounts, double pane windows, material choice, and lack of acoustic tuning/suppression between the cabin and suspension. So, you would be correct that Corvettes are a little louder on the inside. It's fine for some people and for others there are solutions to make it a bit quieter. A sound deadening package, from what you asked about, is a great way to cut down noise from what I've heard (or haven't heard?
), and they don't add too much weight to the car, or enough weight to matter, unless you are trying to catch each tenth on a track.
As stated by others, changing to a more flexible, lighter tire (ei, non runflat) is also a solution to lessen noise in the cabin.