For what it's worth, Mats, I stick almost entirely to Kawasaki parts. The few changes I've made to my Versys have to do with touring comfort such as taller windshield, higher seat, lower pegs and mud flaps to keep me drier. Other than that my bikes are pretty well stock.
For some people part of the fun of bike ownership is personalizing, upgrading and modifying. However for many that is an option, not an essential.
Even Gustavo, who has ridden a considerable variety of bikes and knows about aftermarket stuff, has ridden my high mileage '08 for a few thousand k.m. and is coming back for more this summer. His comment after his last tour was to the effect that he wouldn't have known that the bike had over 200 000 km on it had he not checked the odometer.
The Versys is safe and reliable for very high mileages right out of the box. Quite o.k. to enjoy what you have and never mind about the upgrades.