How to quantify the loss in productivity due to time spent on writing proposals
I think the question is barking up the wrong tree, to mix metaphors.

As you proceed through the researcher lifecycle (Ph.D. student -> postdoc -> professor), your responsibilities will change. For instance, one popular criterion for paper authorship in psychology is that one should have contributed to two out of the following four aspects of research:


Grant acquisition
Data acquisition
Data analysis
Manuscript preparation


As a Ph.D. student, you will mainly work on 2-4. The postdoc will spend less time in the lab (point 2), more on 3-4... and he will also start working on grants (point 1). Finally, the professor will mainly focus on points 1 and 4, to a degree on 3. However, the bottom line is that all four activities are "doing research", since grants are just the way money is allocated to competing research groups nowadays. (Of course, one could argue that it would be better if funding were just distributed equally among researchers, but that seems to be a different question.)

Similarly, in industry you could wonder how much time, money and energy is spent on marketing, pre-sales and sales activities and how all these resources could be much better spent on R&amp;D, production and actually serving customers. But this would miss the point that without salespeople, there would not be any customers, nor money to spend on all the things the non-salespeople like to do. (And frequently, the conversion rate on business proposals is similar to the 1% you quote.)

So: don't see writing grants as a drain on productivity. Writing (and getting) grants is how you get the money to do everything else in science.