I'm not sure that one per decade is unusually many. The US had a lot of bubbles in the 19th century -- canal bubbles, real estate bubbles, railroad bubbles, etc. In all these cases (as with today), there was a real innovation underneath, that bedazzled investors into funding instances of it that didn't make sense.
SIAI benefactor and VC Peter Thiel has an excellent article at National Review about the stagnating progress of science and technology, which he attributes to poorly-grounded political opposition, widespread scientific illiteracy, and overspecialized, insular scientific fields. He warns that this stagnation will undermine the growth that past policies have relied on.
Noteworthy excerpts (bold added by me):
In relation to concerns expressed here about evaluating scientific field soundness:
Grave indictors:
HT: MarginalRevolution