Blaming this on engineers makes no sense. Engineers include some of the most timid, paranoid, self-conscious, and socially self-protective people I know. The people who saw no problem with the auto-follow feature are the people who thrive on living public lives: the masters of social media whose natural belief in self-promotion as the most essential human attribute and the driver of all progress parallels the engineer's faith in human reason. Just as the engineer is so bemused by unreason as to feel justified in excluding irrational people from all consideration, classifying them as atavistic troglodytes, so the bloggers and twits find it natural to brush aside the shy and the retiring as relics of a benighted age in which human beings' natural inborn desire to expose a carefully groomed self to the gaze of hundreds, thousands, millions, billions of people was tragically stunted by the primitive state of society.
The people who approved this auto-follow functionality knew it would piss some people off, and they knew exactly what kind of people it would piss off. They just thought those people could safely be ignored. They thought "everybody" would embrace this new brave new world where all the accidental and unnecessary barriers to extroversion were being thankfully overthrown by technology. Boy, were they wrong :-D and I'm very glad they were; I'm glad I'm not a freak for wanting a little bit of privacy.
[EDIT, hopefully before somebody complains: I know I'm generalizing. I'm perfectly capable of inserting all the necessary disclaimers, but I left them out for readability. EDIT again: Apparently I wasn't fast enough.]