Why is electricity so successful (how to explain the variety of transducers we have discovered) From piezoelectric crystals, to loudspeakers, microphones, hydrophones, strain gauges; electricity possesses the amazing ability to transfer energy/information to and from so many different media. I am awestruck by this.
Is there some fundamental explanation for the extraordinary variety of transducers that man has invented/discovered?
 A: Yes, there is a fundamental reason why electricity is so universal.  It is because matter is made of electric charges bound together (protons and electrons).  When you think of non-electric technologies such as the wheel, realize that the wheel relies on the rigidity of matter which depends on the bonds between atoms which are electric in nature.  So even the wheel is an example of the success of electricity!
Thus, electricity is simply accessing matter in its most accessible form, and this is the "secret" of its success.
A: The point made about electrons being at our level, since we, organic life, rely on chemistry, which means molecular bonding, which means the electron shell is stable enough but not completely inert, is fundamentally correct.. 
From a technological and historical point of view, I would just like to add that electricity could not be useful and could not form an important part of our life until the electric generator and the electric motor was invented.  Scientists of course were interested in electricity, and batteries and generators had been invented, (the first electric generator by Hyppolite Pixii (one of fifty million Frenchmen who could not be wrong) but this did not lead to any penetration into the ordinary world of society.  But then the electric motor was invented and now electricity can become important in real life. http://www.eti.kit.edu/english/1376.php seems interesting.  
