... It is a classic Chevrolet, but those options are closing up now that virtually every postwar vehicle of significance has been released (or re-released.) Where once the late-great Chevys and post-smog mid- and big cars were a charming curiosity, thanks to lowriders and popular culture, they have outstripped the Tri-fives in popularity.
... It is a licensed property of a popular entertainment franchise. The chances of a 1976 Torino getting kitted before Starsky and Hutch (which didn't make it into the WalMart spot, curiously) were a full 0.00. Attach a franchise to the subject that does the marketing for you (Batman, Smokey and the Bandit, Bullitt, Transformers) and it would be hard not to give it the green light,if there were even minimal product line extensions aborning.
... It is a pickup truck or utility. They were made to be kitted. Multiple years used virtually the same body and trim, with only minor variations. There are uncountable variants of bed configurations and build options which can be managed inexpensively. Take a poll on this board of your top ten build plans for, say, a Dodge D-100 or Power Wagon, and I'll bet the overlap is tiny between respondents. (I confess to a fair amount of surprise there isn't more take on the CJ-series Jeeps.)
All the rest of the field wouldn't pay the bar bill for any of the above. The hobby is different today than it was even a few years ago, much less a decade or two. Think about it - the great Mueller/Montgomery era subjects are 20 years old this year. Moebius has a new Chevy II coming, and maybe one or two car subjects more.
So, if you want a Rivvi fastback, get out your keyboard and write the screenplay with a superhero that drives one.
Sic gloria styrene...