In other MMO's that I have played (ex. SWTOR, Wildstar) the option to keybind SHIFT + Mousewheel UP/DOWN was available. This made it very accessible to essentially add two additional mouse keybinds without having additional mouse buttons, easing the ability to move while using actions.

Please consider it! Thanks.

P.S.
I do already have a 12 button mouse but using the MW keybinds I find even easier.