Why on earth would Europe be "a single entity" ?! The more you are forcing it to be (like pretty much a Soviet administration), the less it is working...
All the "European success stories" are things that were created by what you call "loose cooperation between many countries", like Airbus, which is indeed the way to go.
The EU bureaucracy is a catastrophy for European innovation. The more EU there has been, the crappiest the ability to create wealth/innovate has become. Europhiles like to boast about Airbus or Ariane as "European projects" but they are not, they are inter-states collaboration, and were create when EU commission didn't exist with its vast bureaucracy and it's never ending forms to fill. Can you name one Brussels backed project that went somewhere?
All the "European success stories" are things that were created by what you call "loose cooperation between many countries", like Airbus, which is indeed the way to go.