Thank you! I must admit I find the disparagement of philosophy tiring and irritating, especially when it comes from people (self-proclaimed empiricists) who really ought to know better. I am happy to hear my frustration has not gotten in the way of an interesting discussion :)
>It's difficult to reconcile the lagged "observable usefulness" of philosophy with its actual usefulness.
I don't think there is a lag in usefulness (observed or otherwise), when one knows what philosophy is, and appreciates the deep dependencies between it and its sub-disciplines.
Rather, I think people confuse usefulness with certainty. By that logic, I could discount the whole field of science on the basis of the inferential leap. Although science is an iterative process, we cannot be certain that it must converge on truth (though I think it probably does). Given that, the mathematician could look down his nose at science and say "Ha! These fools can't even prove anything!", and in so doing be just as much of a fool as the scientist dismissing the philosopher.
(For the avoidance of doubt: I understand you are not such a person!)
I do think people's critiques of philosophy stem from a need to be pragmatic, which ironically is itself a philosophy. It's difficult to reconcile the lagged "observable usefulness" of philosophy with its actual usefulness.
That which is useful is generally ignored as its been so ingrained in the psyche and that which is seen to not be useful is usually controversial and hasn't made itself to be the "norm" as of yet.