An independent and capable european defence structure is mainly a political subject.
So as long as it is not politically beneficial, it wont be done.
And there is no credible military need/threat in sight to give it a political push.
On the other hand, it provides great political risks for its creators in the current western continental european environment/sentiment.
The UK's command and control structure represents the only nation (including France and Germany) with the ability to more enmasse and run an operation overseas, they represent the single largest leadership and back of house contributor to ARRC.
The problem with the 1.8 million standing army in Europe is just that, it's 'standing' . Any asymmetrical foe is going to attack a countries weak points, which in Europe's case will be sovereign assets outside continental Europe.
If the US adopts an ever increasing isolationist posture and decides it's had enough of bailing out Europe coupled with a sudden spike in attacks against European overseas assets (Embassy's, expatriate communities, commercial shipping etc), then the current 1.8 million 'standing solders' bring absolutely nothing to the table. The European Union military decision making is on a par with the UN, by the time the liberal elite have stopped crying into their coffee the war is either over or one side has been eliminated in a premeditated act of genocide (Rwanda for example). The European nations do what they always do, gather in a huddle, wring their hands before finally looking across the Atlantic for help. Name a single major contingency where the Europeans have collectively got off their arses, bit the bullet and done something militarily decisive since WWII (I'm not talking about individual nations like the UK in 82 and Sierra Leone or the French raids in West Africa)?
The current European collective military set-up is a paper tiger, there to defend against an unlikely threat (Russian invasion), whilst ignoring the clear and present dangers in Pakistan, Yemen and all and other looming failed States. Sooner or later igonoring the uncomfortable truth is going to bite the continent hard in the backside.