It reminds me of how when the one guy, Brad Wright wanted to do a Stargate series, they saddled him with a partner and said "You two work together now" only in the case of the expanse, it happened organically.
I also find the blend interesting because I like techno thrillers and stuff like Clancy where they get into the details and most things are clearly explained.
The original guy, Franck was like that, writing systems and technology, and putting the "hard sci-fi" coat of paint on it,
And the other guy, Abraham is a feelings and experiences writer. More "Sensory" than nuts and bolts. He's the one who keeps you on the rollercoaster, instead of describing it.
I also found it interesting Franck kept trying to get others to play in the sandbox, and then would get angry when writers wouldn't write things the way he imagined them. He even admits he dislikes writing, and initially disliked his eventual partner, Daniel Abraham.
The other thing I found interesting was how much Franck interacted with the community, throwing poo at the wall and seeing what stuck, and still ended up an assistant to GRR Fatman. Fatman has made several angry blog posts about sitting on what you have and not letting fans give input, to the point his official position is that fanfic of his work is "not allowed".
In fact, Fanfiction.net used to remove ASOIAF fics. One benefit of the HBO series was that writers could slap "GOT" in the category box, even when they were writing about characters who never showed up in the show, like Aegon. (No, not Jon, there was another Aegon)
They also liked the old crunchy Sci-fi, the old school stuff like what I remember reading in back issues of Amazing stories magazine.
I have to say, as much as I love space opera, I wasn't really a fan of the old crunchy stuff. I liked some Lovecraft, even if he was human garbage, but Bradbury always seemed cloyingly treacle sweet, more sentiment and whimsy than I like.
I liked 2001 a space odyssey, which was Clarke, and bless'ed HATE anything by Heinlen. I do find it amusing that fans of Heinlen hated the Starship Troopers movie, when I thought it was a lot of fun.