That no central planner can know how much "ought" to be spent on research.

Since no one is arguing for complete central planning, I don't see how this is relevant.

I don't know what people would spend their own money on. That's the whole point.

You are missing my point, maybe I should be more explicit: You have a tiny portion of GDP going to research, and most of those resources go back into the economy.

Oh every group of rent-seekers bleeding the polity dry claim that they've only made a small nick

Missing the point. You claimed that academics getting tax money for research necessitated the creation of tax payer watchdog groups. The point is that since there are much larger interest groups getting much more money who are much more effectively organized, the watchdog groups will be necessary no matter what.