This is true, the PS4 Pro solution is hardly elegant. But at least it is something a user can do. The XBX is always down scaling from a higher resolution and while it works great in most cases .. we at least have a case of two where there's users asking for a native 1080p mode. Considering how user-friendly MS has been, it shouldn't be a big ask for them to have some kind of option for users who may want to disable forced super sampling.
I see your point but I think MS including an option for 1080p to achieve some kind of frame rate sweet spot would court more criticism for them than be beneficial. Hell they get enough flak from enthusiasts over their promises of 4k gaming.