Perhaps what I'm trying to say is "use (or make) appropriate tools for the task at hand."
Of course, in the real world, what actually happens is that old systems are never replaced, only stacked upon, which is why my local auto parts store have POS terminals running fancy web-based UI running on an in-store server which just translates everything into a console/textual terminal session, which in turn tunnels over IP (instead to replace dedicated POTS phone lines) to a decades-old inventory-management application running on an emulator running on an IBM mainframe (which itself may be emulated...)
And of course, the source code to all of those intermediate components is long gone, so no changes could be made even if they were willing to risk breaking the whole stack to improve the efficiency of even one component.
Fortunately, the Free Software Movement is braver than that. Which is how we have the likes of KDE4, Gnome3. And KDE3, Gnome2/MATE/Cinnamon, and XFCE, Enlightenment, and many, many others.
We control the entire stack by virtue of having full source code to everything, and the rights to change it however we like. It's downright stupid to cripple our primary advantage by treating any part of that stack as a sacred cow that can't be slaughtered.