Eh, people manipulate the cup in ways that are not negative for their team in general. Keeping quality low and buying new players after the cup drawing is not the same as getting relegated in order to promote again.
I do agree with the point that people are going to abuse this. But then again, my opinion is that abuse should be punished in a certain way and not necessarily the system that they abuse. Considering the amount of people that play this game and the lack of visible effort on the side of Nordeus, I don't think it's likely for them to be able to deal with abuse in any form though.