My pet theory is that playing a musical instrument is less common a hobby among programmers now than it was a generation ago, because now programming tends to be associated with "Computer Science" as its own discipline, rather than a subdiscipline of math.
I'd say you have that backwards. Mathematicians and Computer Scientists have always been interested in music; but Programmers haven't. These days if you look around a computer science department -- at least, if you look at the students -- you'll be looking mostly at programmers, not at computer scientists.
When I was in Oxford, I saw a mix of "people interested in computer science" and "people interested in programming" -- and as far as I could tell, every one of the CS people was interested in music, while not even one of the programmers was.
I'd say you have that backwards. Mathematicians and Computer Scientists have always been interested in music; but Programmers haven't. These days if you look around a computer science department -- at least, if you look at the students -- you'll be looking mostly at programmers, not at computer scientists.
When I was in Oxford, I saw a mix of "people interested in computer science" and "people interested in programming" -- and as far as I could tell, every one of the CS people was interested in music, while not even one of the programmers was.