It really is. Usually most companies don't give a fuck about their TV counterparts. Even in the contract with Netflix, the shows are all one-and-done deals. They don't make anymore.
This series got a series of shorts, a spin-off that's basically a sequel series in design, another kiddier spin-off, an interactive special, tons of merch, and a movie that Dreamworks INSISTS putting on theaters only. Even Trollhunters' upcoming grand finale movie is just coming out to Netflix. I work at a library and girls check out the Spirit books constantly.
I guess that's also why Twitter is so salty about it. Any of their beloved shows (She-Ra, Trollhunters, the three people left who care about Voltron, etc.) just got their usual episode order and that's it. Dreamworks just keeps milking their Spirit cash cow.