I'm sure there was a 'low disruption path' from 2001 to today but I apparently missed the memo :-). Window system churn Gnome->KDE 3 -> KDE 4-> XFCE, script churn (the whole systemd debacle), USB device churn and device feature churn (mouse tails? mouse scrolling? click to focus, focus under, hover focus?), and display driver churn especially with multiple displays and driver churn. (I've got two in an apparently freakish over / under configuration :-)