If I may disagree, first and foremost it's good to know at what airspeed the aircraft can safely get airborne and control it's direction. If you can't do that then there is not much point in having a V2 speed.
If we then use this information together with other data to be able to determine a safe V2 speed that provides a safety margin on various elements while providing us with a positive climb gradient.
Anyway it's a bit of a moot point, chicken or egg discussion.