I'm pretty sure the main reason for throwing out old tools that still function in favor of the new hotness is developer boredom.

This is why my teams always provide explicit opportunities and spaces for professional development. People should have the opportunity to stretch and grow; if you don't provide those opportunities explicitly, then your most motivated employees will find them implicitly. And you can't afford to not keep your most motivated employees, so you'll end up paying with tech debt instead of Engineeer prof development time.