this means that proper use of your tank stance mattered, and the fact that you needed knowledge/experience to know when and how to use an ability is called depth. Also their depending how the situation changes, (level of enemies vs self, dmg potential of enemies, playstyle of dps, content type) whether you use it or how often you use it changes. thats depth.
is it the hardest decision possible? no. but removing that adds less depth to tanking.
I'll also point out most of the reason these skills are not well implemented is because they designed encounters to be generally simple.