First of all, it is inefficient when you're attacking the same enemy. Attempting (and missing) with your normal sneak attack, then attempting an off-hand sneak attack requires 4 clicks. Click the icon -> click the target -> click the BA icon -> click the target. Whereas, with a toggle, it requires 1 click: click target (with the "attack with both held weapons simultaneously" toggled on.)
Second of all, it exacerbates the problem of hotbar-real estate by needlessly adding another icon. Now sneak attack takes up 2 icons.
Wich both are those Quality of Life improvements i was talking about ...
Namely, reducing amount of buttons (or clicks, w/e).
Thirdly, it runs into a multiattack problem: if your rogue has two main-hand attacks (from haste or multiclassing), they'll still only be able to sneak attack on one of them and if they miss they get no sneak attack damage.
I dont quite understand where did you get this. O_o
I personaly dont know (yet) how multiattack will be implemented, if you do please share it with us ...
Also, im not quire sure about this, since i dont use the potion (not remembering the name, that one that gives you second Action) too often ... but as far as i know, Sneak Attack should not be consumed if your attack miss ...
So i dont quite understand why would they "get no sneak attack damage" ... they just miss, therefore they get the chance with second attack. O_o
Finally, and perhaps most importantly, it still doesn't work with special attack-action abilities gotten from multiclassing, special ammunition, etc. Since you can only click one icon for an attack, you'd either be able to sneak attack or use that ability when you should be able to do both. E.g., a rogue-battlemaster figher wouldn't be able to sneak attack + menacing attack at the same time.
As i said in Edit ...
