Consider that, if V1 is marginally less than the (real world on the day) Vmcg, then you might have a control problem sufficient to
(a) give you a good fright (if you're lucky), or
(b) roll the aircraft into a smoking ball in the grass off to the side of the runway (if you're unlucky and/or not highly skilled in the tap-dancing required with a failure in the near Vmcg region
If you are a few knots slower .. my money is on (b).
Which leads to one of the advantages which can be arranged by using derate.
Not too sure which reality your concern relates to .. but the above is the real world reality, I'm afraid.
Your call.