I suspect most of us are upset not at learning a new thing, but dealing with brand new bugs in new unexpected ways. Learning a new thing has never really been a problem -- fighting instability in new software has always been the issue.
Speaking as a distribution developer, I can say that systemd has bitten me in multiple ways due to upstream bugs that are either ignored or left to rot for quite a while. I've had to resort to patching them, or working around them, which makes things very difficult to live with, especially given the pace of systemd development and feature additions.
The older software had a number of bugs, yes, but they were well known and battle tested. In short, it's not "I don't want to learn" -- it's "the new shiny has a slew of unknown bugs we can't easily identify and fix".
[edit: removing bits of incendiary text]