SS also affects DoT damage (but not much), also it's easier to handle mechanics during/after casts and occasionally you'll get one more attack into [random buff].

Also you end up having more and more SS anyway, since every crit-gear 230+ is either with acc or SS. And if enough acc, you can only go for SS+DET usually then. (Only Crit/Det are weapons)

My BiS: http://ffxiv.ariyala.com/UVYT with 1012 crit + 763 SS while at 593 acc.