What are some reasons TV is good for children?

It has been said that unrealistic TV (i.e. Cartoons that show violence etc.) are bad for children's health but realistic programmes like documentaries can be good. Of course it is a case of checking the content- some documentaries aren't suitable for children so be causious with regards to what they watch. Also be careful with the timings they watch TV for- TV should be watched in moderation- (i.e. don't let them watch hours of TV a day). A maximum of 2 and a half hours of TV a day would be plenty.