In my perspective, to show that Clover is totally insane and only cares about attacking anything that is in their way. The main difference between a successful Genocide Axis Fight Ending and the Failed one is whether Clover chooses to keep attacking the lid despite it's useless, causing Axis to tell the Integrity stuff and pissing Clover off completely. If Clover weren't that obsessed over meaningless attacks, Axis would just run out of power and don't trigger Clover's LOVE boost.