[sybir]

It's not an option package, it's representative of preparation of the vehicle.

It's not the same as calling something a Corvette Z51 (which would be incorrect)
However, is it a Camaro, or a Camaro Z28?

The rest is not superfluous. A Subaru Impreza RA doesn't tell me if it's a WRX, if it has the additional prep by STi (which is considerable) and doesn't tell me if it's a limited edition car. It also doesn't tell me if it's before or after the facelift, what other cosmetic and running gear changes were made, what the base motor is, etc.

The descriptive names adopted by Japanese manufacturers help to identify a vehicle when it's not sitting in front of you to look at.
If you actually understand what's being discussed, it's almost like shorthand, similar to referring to everything by engine and chassis codes.