I think Macron wants an EU army because he’s afraid that civil unrest in France is not going to go away by itself and that at some point he won’t be able to count on the French army to put down a rebellion by French citizens… so he wants an integrated EU force to do it.
This is a very important point. Austerity (aka the erosion of the nation-state) isn’t going away. It will be rammed through with violence if necessary. It’s only fitting that the violence is as supra-national as the forces it serves.