Effin, I think what you are experiencing is some frustration being vented by those of us Genesis owners in a somewhat silent majority - those who have never experienced any unusual handling characteristics in our car and happen to like the way it rides. There are a number of individuals here who seem to go out of their way to discourage potential buyers - if you think about it, this is the only logical reason for former owners of the car to continue posting here.
I'm sorry to hear that you didn't like the way the Gen rode, but must echo the opinions of others who pointed out that this stretch of I-20 is just a miserably bad road. I've been over it in my V6Gen, and my car handled it better than all of my former vehicles (96 Maxima SE, 03 Murano, 04 BMW 528i). In fact, I think the Genesis has a better overall ride than all of the aforementioned vehicles on any road surface I've been over in 18,000 miles of driving. If you want to
really feel a vehicle "porpoise," try that stretch of I-20 in a 2003 Murano - but wear a helmet, because you'll need it. I find it somewhat sad that a very vocal minority of dissatisfied prior customers are creating a reputation for this car that seems unwarranted to me. I would imagine some other owners feel the same way and have expressed their frustration in a manner that some forum members/visitors may find inappropriate.
One's feeling about any car's suspension is inherently subjective, and each buyer has different expectations. I happen to like the suspension on my Gen better than any other car I've owned, and literally every single passenger I've ever had in the car (dozens) have commented favorably on the ride. It seems to me that potential buyers are getting an inaccurate impression of this car because those of us who are satisfied owners tend also to be quiet. Hence, my post.
BTW, for you conspiracy-theorists out there, please be advised that I don't work for Hyundai or any dealership.