That misha guy bitched about the Supra early on saying the ONLY fix would be revised subframe - fast forward, sub frame comes to market and continues to bash the car because, I suspect, there are enough people wanting to hate on the this car - making it good click-bait.
Without replacing the subframe, there are plenty of people saying this is a capable track car with just a couple provisions - with times to prove it. To me, it's right in line with the wind buffeting issue.. if you feel as though it's a problem, then fix it.
From everything I've seen/heard bumpsteer can be mitigated without having to rework the subframe.
This is a Z4 after all so some level of numbness had to be expected.
Not to insult but have you tried anything to fix it? From listening to Jackie, and judging from you avatar, your stance looks to be too low.
Are you running coilovers or just springs? Have you upgraded any of your other suspension components to SPL or something comparable?
This car was not...