having a combo button might not be a bad idea for pve but the only problem i could think of is then the game have preset the way you are suppose to play and theres no freedom. now if they give us a customizable combo button then that will be nice!
you can somewhat make a similar fashion combo button macro like for mnk but theres some slowdown issue. because the macro will search/try to active the first line action if its ocd but if its not then it will try to active line 2 and so on. anyway what i want thr customizable combo button is you set the first button press its this action then after cast/gcd it will be another action that you choose and so on amd with no delay at all