So my question is- Bridgestone tires are actually pretty good.
So why are the ones on an $80K Denali so bad?
Many OE's have their own set of internal requirements for tires (either driven by the specific vehicle and/or overall corporate requirements for performance, handling, MPG, etc). If you look there are often multiple versions of a particular tire - the "standard" tire and the variants that meet the specific OE requirements. The tires will have a specific marking to call this out. Check out this
Car and Driver article to see more on that. That is sometimes why Tire Rack will show what looks like the same tire at slightly different prices.
As an example, Ford created a specific version of the BF Goodrich All Terrain tire for the Raptor. It was basically the same tire but with a softer compound to improve winter grip/performance. For the 22" tire on the GM SUV's I'm guessing GM (like many OEs) prioritized fuel economy over other factors (grip is a typical trade-off for low rolling resistance). There are many factors that need to be traded off to meet the specific goals: noise, ride, grip in many weather conditions, MPG, cost, load capacity, tread life, logistics of tire delivery, customer desires, OE relationships with tire MFG, etc.
I typically don't agree with the OE set of trade-offs on my tires and rarely pick the OE tire when I replace them. When it comes to MPG, sometimes the trade-off is some fraction of a MPG other times not. I've personally seen my MPG fluctuate by a ~2 MPG with different tires on my other vehicle. So you may notice changes when changing tires and you may not.