Yes, tenure is still needed for teachers. There are lots of laws that will protect teachers (and other workers) against discrimination for many things. But there are no laws that will keep a superior from terminating you for some grand reason she dreamed up because she doesn't agree with your political viewpoints. Tenure, however, does.
Let's use a hypothetical situation for a scenario. Let's say a biomedical sciences professor finds a cure for cancer that is against normal medical science. For years, peer-reviewed papers and experiments go against what that professor decided was a correct hypothesis. Without tenure, a university could fire that professor for being a quack just because his experiment showed different results than others. Instead, professors should be allowed to mess up and come up with conclusions that are different from mainstream science. Tenure is still necessary because universities should be bastions of the free exchange of ideas, not places where professors' opinions are squelched. Tenure is necessary to protect honest professors unless they break the law. Consider tenure to be the "labor union" of academia.
I think overall while there are protections that protect against termination I think teachers have more peace of mind with the tenure system, I think we should make the standards for getting tenure extremely tough so only the best of the best are able to get it but overall I think tenure is beneficial.
I do not believe that teacher tenure should be a thing. The only thing that tenure accomplishes within schools is allowing bad teachers to continue teaching. After a year of teaching it becomes near impossible to fire a teacher. They can sit in class showing movies all day and there would still be nothing that anyone could do.