Do people even have a formal responsibility to be inclusive?
I don't know what you mean by "formal responsibility" in this context. If you mean a law or contract, probably not. But, is our responsibility to each other limited to formal responsibilities? Imagine how crummy your life would likely be if those around you only stuck with those signs of respect they were required to do by law.
Also, this discussion, and the formation of the opinion of folks out in the public, is not a formal process.
In my heart I know that the reason that WotC/Paizo are prioritizing inclusivity is because the market demands it, not because it has inherent value to them.
Well, note that the corporate entities themselves don't do the writing. I recall noting that members of the WotC staff had said they were making changes they wanted to make anyway, and had been suggesting for some time. So, the authors themselves may find it has inherent value to them.
Let's not get things twisted about what motivates a corporation with shareholders. So, let's not pretend that if the zeitgeist was going the other way that WotC wouldn't follow.
To suggest that corporate entities only act on market demand is to suggest a grade-school level simplification of creator/corporate/market dynamics.