Bigger edges give a bigger middle in size on the face, but decrease the power from the centre. It is a trade off as you cannot take wood from one position and not have an effect from the action.
The bow is a result of 3 possible actions,
1, The old fashioned bow was caused in the dead flat face by repeatedly striking the ball in the middle and was considered a sign of a good batsman.
2, The Asian bow is created by increasing the pressure of the roller during pressing in the middle and also from planing the face out to create the above bow artificially.
3, The Resulting bow is due to the pressing process and is a result of the pressing method rather than any desire the create it.
The bow itself adds no benefit, unless you are a spiv retailer and they don't half talk it up without knowing what it is.
Big edges are possible in Pro bats due to low density, they are in shop bats due to the better willow conditioning and the desire to copy the Pro bats.