agree with all of this but it is annoying that D- cannot be set to be default. Driving in D-, use cruise control, then back to non-cruise driving and you are in a different mode (D). It’s dumb.

Again, my original opinion of trying to override a safety barrier is kind of dumb.
In automatic, adaptive regenerative mode (D when the mode set to on) will sail by default which is technically the most fuel efficient mode of regen (no regen, just free roll) and it will apply as little regen as required to stop by the next intersection or to maintain proper following distance to the car in front of you. How could/would you improve on this kind of regen braking in any kind of manual format?

The only reason I would envision someone prefer to use D- over the predictive one is consistency. But it will be less fuel efficient when there are no obstacles (nothing is more efficient than free sail) and it will be more dangerous than maintaining proper distance when there are obstacles or you have to apply brakes manually.

The adaptive engine brake will actually start decelerating much earlier than you would with brake pedals to ensure that the braking power never requires more than 120 kW of braking so it can use strictly regen braking to stop at the intersection. On my buddy's F150 Lightning you actually get a % after each braking maneuver as to how much of the kinetic energy could be reverted back into the battery. If you're gentle it is at 100%. If you're hard on the brake and it has to use real brakes it will dip into the 90s. Very neat little display.

The only issue I have found with the auto regen is that when you're also trying to add manual braking to it, things get a bit wonky and it feels weird (brake gets stronger or weaker at the same time). When you're applying the brakes it will essentially override the auto brake/regen and if you are gentle on the brake pedal there may be a moment where your brake pressure is less than what the auto regen was applying and since the pedal overrides the auto braking the brake force becomes less than what it was as you're pushing on the pedal. And as this happens you start applying more brake and essentially over brake. As an engineer I'm not sure how I'd solve this problem myself but this is what I have experienced in the few hundred miles I got to drive my wife's car.

Yup, when I am on less congested highways I will let the auto lane change do the work for me and I will turn off auto lane change once traffic builds. As L1Wolf pointed out, above, it will want to move you over sometimes when you don't actually want to yet. Also, if you're running navigation and auto lane change, the car will automatically put you into the correct lane as you approach a highway exit, which is nice.

That is my perception, too.

FWIW, this ('D auto') is the default mode even in cars without the ACC option.