That is because they are not interested in fighting. The day India/Pakistan/China/Russia have the social development of that level, they will too realize that Nukes just a way to boost your ego. More like, compensation for something you couldn't have or have.
Britain and France know their Nukes are no longer relevent. But since they have joined the world's police force i.e. Uncle sam, they tend to keep it. But it is nothing in size compared to what USA has.
Most European nations have steadily seen a decline in their military assets, air, sea or land.
For them, war is nothing.
You tell me, who is going to invade Germany? India? Russia? China?