I understand the concern for potential compromises completely. While lots of things can easily scale up or down with power (texture detail, resolution, framerate, etc.), some things don't - world size and density, artificial intelligence, lots of NPCs/enemies on screen, etc. Those are things that have to be designed around your lowest common denominator, and then scaled UP from there. This is also why some cross-gen games have historically been developed by separate teams for each platform.
You mention one good point, which is that with Microsoft putting all of their games on PC now anyway, their first-party games were never going to be designed with solely the XSX silicon in mind. However, what you CAN do with PCs, is increase the system requirements for your games. An Xbox One is always going to be an Xbox One.
I do think the effect of Microsoft's cross-gen plans is hugely overstated by (usually motivated) parties who think it's a massive mistake. It's one year and first-party only, meaning it's likely to affect, what? 2-3 games at most? And the extent of an effect it will have is directly tied to what kind of game it is. I don't think a Forza Motorsport title would be massive affected by scaling down to an Xbox One, for example. A Forza Horizon game would be much more impacted by it, because it would dictate things like how big and geometrically complex their open world can be.
All we can hope is that, when it comes to their cross-gen games, Microsoft are throwing enough development resources at them to make sure the next-gen versions truly feel next-generation.