You're not supposed to notice it. It's not a "sport" mode where the suspension is tightened up like on some performance cars. It simply lowers the car at speed to improve aerodynamics and therefore range. There is a small decrease in body roll since the car is lower but the MS already has so little body roll due to low center of gravity only someone w/ a "highly tuned butt" would notice. If you are driving a fair distance you would notice it in lower power consumption but for most people they are just complaining because something was taken away from them by Tesla without their agreement. To some people it is a scary idea where the manufacturer can change "your" car long after you bought it without your permission.
I don't think it's without your permission/agreement though. Some people have been refusing the 5.8 update specifically for that reason. Personally, I'm glad my car actually improves over time.