It's not, though. That's where you're wrong. Nobody in the production of this film is all that concerned about the old-school fans. They're incidental. A nice bonus if they show up, but not a group to be catered to or really concerned with at all.
Why, you ask? Simple. The whole point in the reboot is to expand the brand to people who aren't already fans. The fans will show up, or they won't. Numerically, there just aren't enough to warrant allowing fan sentiment to dictate the course of the film. If there were enough fans to do that, we'd be watching Ghosbusters 8 by now. Ghostbusters is a niche property as far as hardcore fans go. However, it's an extremely well known film and well known brand. But most people aren't really "loyal" to the original stuff, so they don't demand anywhere near the fidelity to or respect of either the original films or the fan community itself. They're a niche market, basically.
This film, though, is meant to relaunch a brand and build interest in a whole new direction for the franchise. It's meant to be familiar to casual fans of the original, but something new that they can enjoy, and from which further films and merchandising can be launched. Seriously, the studio sees huge potential in the brand itself. Video games, cartoons, toys, TV shows, etc. The sky's the limit, really. That's because the brand itself is really familiar and carries with it a lot of goodwill. I'll bet there's a market analysis in some file somewhere at Sony showing the market potential for the brand based on projections from the goodwill alone, and assuming a decent enough product can be produced to get the ball rolling. Those dollars aren't based on hardcore fans; they're based on potential new fans and old casual fans who've seen the original film maybe 3-4 times at most. Probably fewer than that, since it doesn't tend to get a lot of TV airplay.
That's where this film comes in. It gives people a modern product, a new story so they don't have to follow the old stuff or wonder if they missed something somewhere, and it allows the creators total freedom to springboard from this film in any direction they please. So, yeah, they don't really give a rip about "the fans." Not the ones you're talking about, anyway.