The good thing about them is they have small increases you can do from factory. You might buy the Ford Berlina for $20k and for an extra 2k you can get leather seats. For an extra 5k you can get another badge and red or blue backlights on your dash and bucket seats. However at the end of the day, the still are a Falcon or a Commodore, regardless of whether you paid $140k for a limited release one which is slow anyway.
How many people do you know that aren't into cars can tell you the difference between a R32 and an R33 without looking at a picture? To the majority, Skylines are just Skylines, whether you have a GTS, GTST or GTR, they're all the same. Some make tu tu sounds and some don't.
Like the other guys have said, they are practical, you can throw a towball on the back, pick your angry single mother and her friend up from the city at 2am and all those other fun things that come along with owning a sedan.
If you know anyone who owns one, get in a worked Xr6 turbo and tell me you don't want one.