I agree having optimum flex temp/flap setting is the ballpark of my expectation for a performance tool, as indeed most of the time v-speed can be calculated in fmc. However there're situations that FMC speeds are not correct, notably for an intersection take-off, runways with clear way or obstacle limited take-off, since fmc calculation always assumes balanced field. Thus to make full use of TOPS' intersection optimisation, an accompanying v-speed calculation is needed.
Moreover, Airbus MCDU doesn't calculate v-speeds in real life.
Moreover, Airbus MCDU doesn't calculate v-speeds in real life.