my XPS 15 7590 is dead flat. I have encountered ones that rock, but it's because the owners would slide them across tables and wear the rear 'table-leg' bumper unevenly. I tend to pick the laptop up and re-place it when I need to move it rather than slide, and i've had good luck.
Now, I agree that kind of thing shouldn't have to be thought about as a wear item -- but it seems to be one.
>>but it's because the owners would slide them across tables and wear the rear 'table-leg' bumper unevenly
I assure you all of mine did that straight out of the box. When the second one did it I was like "Huh, what are the chances" but I almost expected it with the third.
I assure you I do no such thing, and two for two my XPS laptops "rock" on the table.
Neither laptop has any wear whatsoever on the rubber feet from sliding them on a desk, or on anything else for that matter. I'm a software engineer, not a savage.
From my rudimentary testing, the front right corner is a little bent upward compared to the rest of the laptop. If I touch that corner with one finger it rocks, on both models and on any level surface.
Both of my machines are older than your 7590 but they both did it since new.
I got a 2020 model this week when the hinge broke on my XPS 15 but I'm yet to test if it suffers the same issue.
Now, I agree that kind of thing shouldn't have to be thought about as a wear item -- but it seems to be one.