Tenure was a reasonable concept. Professors needed the ability to conduct research and further their field without having to worry so much about teaching. Great! We have universities to thank for MANY of our conveniences we enjoy today, and many other critically important things. However...
It's become a bit of a joke. It's more about "staying long enough" than actually accomplishing anything. I attended a top 20 MBA program and was surprised (and not surprised) at the number of professors who had little or no actual real world experience outside of academia. One professor I had Graduated from Florida in 2007, got a masters in 2009, then got a Phd from Iowa in 2013, and has been teaching ever since. No job listed on his profile other than professor. He had not yet achieved tenure but that was clearly his goal (he wasn't shy about saying it). I took an organizational behavior class from him. Yes, we were learning about managing organizational behavior at a top 20 MBA program from a guy who had never been a manager, let alone an HR director. He sure had read up on it though...
It always amazed me to hear tenured professors be introduced, or when they'd introduce themselves at the beginning of a term. They'd have all of these awards that had been given to them by other groups of professors, and been published in "prestigious" business journals that no business executive had ever heard of. It's like a club of you scratch mine, I'll scratch yours, and we'll all scratch each others... It's not that the information they were sharing wasn't good, it's just that most of it is theoretical since it was largely based in research and not real world application. It's not true of all professors.
I don't think this was the intended result of tenure when it was created.