Ok. look at this:
On the right of this combat log you see avoids, which shows how many times each ability missed or got avoided by the bosses defense chance.
The only attacks used that would have benefitted at all from Accuracy, were Rifle Shot and Carbine Burst.
And I swear to you, this Operative was running with 0 accuracy rating in its gear.
Mostly healing gear with few campaign armorings swapped to get the dps set 2 bonus, and I say again, no accuracy rating at all in its gear.
Even with that all other attacks, except those 2, did always hit.
Now you can also put it this way, missing 10% less on one ability that does only 5% of your total dps, would increase your total dps by 0.5%.
So yes, accuracy will do something for you, but you should start adding it to your gear only after your surge is well above the soft cap.
So this is how it is right now. In 2.0 it will of course change and then accuracy will be more important.