In the wet the suspension has to work the same way as the driver, transitions have to be smooth and controlled to prevent sudden loading of the tyres and maintain grip. Stiffer bars load the weight bearing wheels too suddenly and it's difficult to reach peak traction without overdoing it.I don't understand that? If the body of the car rolls, the centre of gravity moves towards the outside and loads up the outside tyres more. I thought the whole point of keeping a car flatter was to keep the weight more evenly distributed on the wheels and keep the tyres closer to vertical. Otherwise, what is the point? And I don't see how this would be a benefit in the dry but a disadvantage in the wet. The principals are the same.
Anyway, I'm not asking about how to upgrade my car. It's a hypothetical question about the relative importance of wheels/tyres vs suspension itself.
There is less feel for the margins of grip too.
I noticed the difference with adjustable Konis on my MX5, it was far more predictable in the wet with them set softer.