I feel like im 1 shotting everything on P8 as is and I dont have torch/anni/gcs or even a shako and arach yet.

+ skills feels like its barely a big difference to my damage and the only thing that really matters is -res like Infinity/Griff/Mosaic claw rolls etc. Is it really worth to take MA skillers? I almost feel like just stacking life/res scs or mf charms, no?

you gave the answer yourself. if you really are already oneshotting, there is obviously no need for further dmg