This may so obvious as to be wrong, but it gives you an albeit small cushion - V2 is really the bare minimum - and one needs as much as one can get in the case of an engine failure or any kind of master caution on takeoff.
And your rule about V2 is nonsense. Unless you remember it incorrectly - you need always to be at or above V2 once airborne - it is after all "takeoff safety speed".
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