Today I read this paper that was published long ago in The Journal of Biological Chemistry. The title reveals what the paper is all about. I really enjoyed reading it and there are a few parts that I think the author states the facts about Bioinorganic Chemistry very clear. Like this one :
"... there was a gap of about 30 years between the 1940s and the 1970s when there must have been a great step forward in appreciating the significance of transition metals in biology."
But, as he further mentions, an important reason for this was that the spectroscopic techniques were not developed enough to study the metals in proteins.
Anyway, I suggest that you should read this paper if you are interested in metals in biology. It also has really cool details and stories about important names in chemistry/physics. So, it was like reading an introduction to a science history book and I really liked it.
I think the figure below summarizes the importance of the field.