As a general rule, biology tends to be conservative. It's rare that evolution 'invents' the same process several times.
Gero Miesenbock
For the longest time, neuroscientists were forced to be passive observers of brain activity.
Sticking wires into the brain is obviously rather crude. It's hard to do in animals that run around, and there is a physical limit to the number of wires that can be inserted simultaneously.
I don't know about you, but I find it exhilarating to see how vague psychological notions evaporate and give rise to a physical, mechanistic understanding of the mind, even if it's the mind of the fly.
