I ride year round, so I added things like handguards & heated grips to protect my hands from cold air.
I also added top case on both of my bikes, because it makes the bike much more useful in day-to-day commuting world. You can fit more, and ride longer than if you were carrying all that stuff in a backpack.
So I add farkles purely from practicality standpoint.
1984 Honda CB650sc - Nighthawk - with 33K miles - Fuelly Log
1982 Honda CM450a - Hondamatic - with 11K miles - Fuelly Log
2007 Kawasaki Ninja ex250 with 29K miles - Fuelly Log