The Linux / BSD driven revival of Unix happened, un-fortuitously, just when object-orientation, graphics, UML, patterns, etc, were hitting their peak, largely because they were super successful in dealing with problems in graphic interface design. So these oo approaches became dominant in curriculums and paradigms far beyond their applicability, and no one bothered to study the classics of the previous generation like APUE etc.

Smalltalk and C++ begat Java, begat Ruby/ Python, and now we have a whole bunch of server-side programmers who know how to inherit from multiple base classes but don't know what fork() really does; when these young people (ahem) discover how well their grandfather's Unix addresses many of their current server-side problems, well, they are thrilled.

Let's just say it's the same thing as a twenty something discovering Sly and the Family Stone vinyl in the basement... Yeah, it rocks.