Naive Bayes revolutionzed spam filtering because it is incredibly easy to implement and understand, and was reasonably effective for early spam, not because it was the best model for detecting spam. There's a reason we started seeing ads for "v1agra" and snippets of prose -- it's pretty easy to game Naive Bayes.

On the other hand, the GP's assertion that there is seldom a need for using Bayesian methods is also unwarranted; they are the basis for so many machine learning algorithms in common use -- particle filters, for example.