As a tank I use standard camera and want S to packpedal. If I want to go forward behind me, I use turn around. I use my mouse to move the camera so I can turn around with the mouse and standard camera in an instant.

I find that if I turn on legacy camera I end up running backwards because I was faced in that direction when I wanted to go the other way and I run off platforms and crap. It's also easier to position a boss accurately via back pedaling, where as not backpedaling might move the boss to far or cause him ti glitch and practically get on top of me (e.g. lost boss in AK)