Why? Here's the answer, right at the end of the article: "[Court involvement] really has led to some court decisions that have been quite adverse to employers.” Big Business has so little respect for the public that they don't even come up with a new excuse for taking away your rights; this is the same canard they used last year and the year before.
Whatever legislation is proposed by the Pilot state government, er, the Haslam Administration, will pass; the Republicans have more than enough votes to do basically whatever they want. And what they want is for no individual in this state to have either the right or practical ability to seek compensation for personal injuries.
To paraphrase Herman Wouk, in War and Remembrance [ebook, p.125], when individual rights die, they die like a cloudy day, without a visible moment of sunset. So it is with worker's compensation, and so it has been for the rights of Tennesseeans to see legal redress in the courts.