I don't buy the piracy excuse, especially since RE7 still had excellent sales despite getting broken. More likely it's "Steam version? Oh fuck, that's right... uh... we have no idea how to do that."
Japanese devs are terrified of the PC, they have no idea how to approach it. It took petitions, sales estimations and years of waiting for publishers like Capcom, From Software and Square Enix to feel comfortable dipping their toes into the market.
Considering 90% of this game's hype is in Japan, 99% of Western gamers have no idea what "Nier" is, and the PC is pretty irrelevant in their home market... I think their focus is on domestic sales first. We'll be lucky to see a PC release before 2018.
I'm warming up to playing big RPGs on my PS4 though. Nioh taught me that, while still not ideal, the platform is at least convenient.