The HS30-H model 'Fairlady 240ZG' was a factory Homologation Special, designed, built and sold to the general public simply because it allowed the factory to use similar ( but even more radical ) parts in races where the FIA's Group 4 rules were applied. It wasn't about making the car pretty.
Nissan didn't sell all that many of them because they didn't make all that many of them. They made enough to satisfy the quantity needed to homologate the model. Again, it was nothing to do with looks and looks alone...
Having said that, I happen to find the genuine 240ZGs - as well as the factory race cars that evolved from them - very attractive. A lot of that attraction for me comes from the knowledge that the 240ZG was built for a specific purpose, and that specific purpose was directly linked to racing. Interestingly, I think you'll find that the market ( in Japan - where 99.9% of genuine 240ZGs still live ) agrees, and that genuine unmolested 240ZGs are some of the most valuable S30-series Zs. I'd say that the 240ZG ranks third ( behind the PS30-SB Fairlady Z432-R and the PS30 Fairlady Z432 ) in a Top Trumps style S30-series Z desirability / value index.
Personally speaking I appreciate ( love ) the unmolested 'stock' S30-series body too. That's why I own both.