well there is a matter of cost/time and the increasing precision required to do more complex designs…
and that brings up the other issue, whoever designs the bar when it’s not adjustable has to be working on a young chassis that hasn’t had the crap beat out of it so it’s more or less factory perfect measurements… anyone doing it on a 15yr old car will of course be off a bit and adjustability is nice to have even just for fitment regardless of the preloading ability
anyway back to the topic, if he wants to make and sell bars with the bells and whistles he won’t have a chance to compete with the chinese cusco/greddy knockoffs
and bas you know there’s tradeoffs in stiffness, you don’t eliminate the force you just move it around, when you concentrate it to a few points in a race car you can control it better provided your suspension and tires can deal with it… most street cars don’t have nearly the strength/stiffness/grip to be able to handle that kind of stress and it’s actually better to have the body twist and deform to absorb some of it, which is something a racecar with a cage doesn’t do