R&D productivity in biomedical science?

The Financial Times has an article today that features a graph plotting R&D productivity over the time from 1950 until now.
Interestingly, there is an exponential decline from some 60-70 drugs developed per 1$bn spent to about one drug today. Apparently this is leading to investments in health and nutrition drugs, like multivitamins instead because of its lower risk.

The graph also features a history of the development of molecular biology along the time axis. It begins with the discovery of DNA structure 1953 and ends with the sequencing of the human genome 2001. In other words the R&D productivity is declining despite fantastic flabbergasting developments in biomedical science.

One explanation for this might be that the prevailing paradigm in pharmacology has been to vacuum clean Nature for natural products that are testing positive in bioassays. By now they have found most of the ones easily available, thus the exponential decline.

My feeling is that we have not yet been able to reap the benefits from the revolution in molecular biology and all the knoweldge we so far got from this field. However, if I am not correct in this assumption it would mean that we are running on empty towards a situation where new "blockbuster" drugs will be hard to find. This would mean a large blow to the usefulness of biomedical science.

In a way we are seeing the same thing in physics with the need for enormously expensive accelerators that seems to exhaust the possiblities of getting much further in science on this front. My worst nightmare is that we will reach a new plateau, like after Plato and Aristotle. The current, almost desperate, scream for innovation is indeed ominous.