The notion of tenure wasn't developed to protect dead wood. It came about because historically it was often difficult to distinguish "fired for cause" from "fired for speaking out in ways that irritate the powers that be." The ability to fire people for cause is appropriate to businesses and startups, and even there we routinely hear about controversies where "for cause" is blurred together with "saying things that leadership didn't like." The tenure system was explicitly designed to prevent that, and yes, the "cost" of that system is that some dead wood will slip by -- but this has always been an acceptable cost. Our society relies on having a pool of people who cannot be easily silenced by their employers. We will suffer when those guarantees are weakened.
On a personal note: I'm a tenured CS professor and make less than half (often significantly less) than what my colleagues in industry make, for a job that often requires longer hours and a lot of travel. I also have had some experience with having my speech restricted by the administration [1] under the guise of "violations of University policy". As a tenured faculty member I stay because there is no other job where I can speak about anything I want, even if sometimes I say dumb things. My colleagues in industry can't do this -- some of them tell me they are scared to even "like" Tweets that criticize their employer. That's messed up.
To those folks who don't care about these broader arguments and think this decision is reasonable, that it "will improve faculty performance," even there you're wrong. If GA becomes the state that doesn't have tenure, all the best faculty will go to other states and/or to industry. Every state university already struggles to get top talent, and now GA has given themselves a huge hiring disadvantage. Whatever "productivity" benefits you might get from greater faculty control are going to be hugely outweighed by the fallout from this stupid (and obviously political) decision. The board of regents knows this, and they don't care.
[1] https://www.cnet.com/tech/services-and-software/johns-hopkin...