Speaking as an outsider, people seem to be missing the elephant in the tutu dancing in the living room.
The EU wants its own military because it can't be taken seriously as a sovereign nation until it has one. On past experience that means they'll work step by step for the next couple of decades until they have it and there is no more RAF or Royal Navy or British Army.
If that's the case, the government may not see the point in spending British taxpayers' money on hardware that's just going to be handed over to Brussels in a few years. Why not let the French and Germans pay for it instead?