Added grip? Maybe. That too depends on a number of factors, but....
Issue #1: Take two books, put them 6" apart on a flat surface and put a piece of thin wood on top of them. Push down. Take the same two books and piece of wood and put the books 10" apart and push down. We learned this in 6th grade science, right? That is what happens to a suspension system when the offset of a wheel is less than is should be. More strain on the hubs, hub bearings and axle shafts. The theoretical lever is being increased. More mechanical advantage is being added to the lever. This also adds to bump steer and understeer.
Issue #2: The steering angle is being changed, yes. By pushing the wheels out from their intended position, the center is no longer the center. A new wheel/tire center is created, but the steering doesn't know that, so when steering the car (if you can picture this) the outside wheel is being pushed forward, instead of just turning, and the inside wheel is pushed backward. To return to center, you have to fight the wheels back in the opposite direction that they were made to go in the first place. This causes additional wear on steering components and a dead on-center feel. And any alignment adjustments would have to take these factors into consideration or they will also be incorrect.
Unless you are willing to redo the whole geometry of the car, I wouldn't think of going more than 7-8mm out of tolerance from OE.