Certification requirements specify only minimum values for V2. Manufacturers and operators often choose to use the minimum value of V2 because it will get the aircraft airborne in the shortest distance.
The disadvantage of using the minimum value of V2 is that, for a jet, it may lie on the wrong side of the drag curve and not offer the best climb angle. Some aircraft use 'increased V2' procedures where a V2 higher than the minimum is used giving better climb gradients but taking longer distances to get airborne. The benefit of improved climb gradient can either be used to improve obstacle clearance or to increase the climb limited TOM, sometimes called the WAT limited TOM.