In this note, we argue that in the future electron–positron colliders with up to two orders higher event rates, the role of the Standard Model precision calculations in the data analysis performed using Monte Carlo (MC) event generators will be dominant, much more important than in the past LEP era experiments. This will require designing, constructing and testing an entirely new class of the precision Monte Carlo event generators for all important processes such as production and decay of the Z and Higgs boson, W pairs and the Bhabha process. We are going to outline challenges on the way to construction of these new MC tools and foresee possible lines of technical developments which will be necessary.