Why are houses gated in France?

Americans love gated communities. French love gated houses.

I think it goes with the phrase 'Vivons Cachés, Vivons Heureux' / 'The less everybody knows, the better off you are' (I apologize for a pretty bad translation). Anyway, the French are pretty private. Take outside decorations for example: ever notice in France that x-mas decorations are always great inside a home, but pretty sad on the outside? People are more reserved in that respect, which also has to do with respecting others. Americans are more outgoing in that respect. Yes, I miss the open front yards like on Desperate Housewives, because that's how I grew up. But there is also something nice about coming home and the comfort of being in an enclosed, private space. If anybody can enlighten me on the sociological explanations behind this, go for it.