Against tough opponents, I agree with you, but for normal games in Serie A or agains weak opponent in CL like Young boys, then Higuain is still good. We (fans, board) all want him out. Problem is that we can not ship him out due to his very high salary and the great amount of amortization cost (36M remaining), and he until now refuses to leave, just like Sanchez (MU), Bale (Real). If he does not change his mind, then we will stuck with him. Any action to force him out will not do anything, as he is 31 right now, no international career anymore, so he will be ok to collect 7M salary for next 2 years and then leave.
We can't do anything about that, so keeping him in the squad as rotation is our only option right now. At least, he is not too useless like Amauri in 2010.