Huh. You’re right, I can’t find it anywhere on the rewards page anymore.
Keep in mind, I first said “to hell with this” back about a decade ago for Microsoft points when they stopped offering Xbox currency as a reward. And yet, it got added back eventually (I have no idea when, since I stopped paying attention to rewards until @divedivedive kept bringing it up).
So it’s possible that they’ll bring it back like they brought back currency.
Also, Xbox Live Gold is still a reward, and that can be converted into Xbox Ultimate. So there’s still an avenue there.