Maybe those who used these expressions were being rather witty, because we are actually talking about the usage of the archaic, best avoided passé simple here? But what do I know?
In all seriousness, didn't sacré bleu come from sacré Dieu? I believe it was used a lot in literature in the 17th/18th century stuff we had to read. (Shows you're well read * Marydoll*, if rusty!). Does the French language in general have more blasphemous expressions?