Maintenance and features.
Here's one thing - I once had an early 80's Japanese motorcycle that had a rod bearing go bad. There was no replacing it short of replacing the entire rod (and therefore piston) because the bearing was just a machined portion of the rod.
At that point it simply wasn't worth fixing - even doing it myself it would've been a lot of work, a lot of risk of breaking screws, stripping case bolts, etc.
It was easier replacing the rod and crank bearings in a car I had at the same time, without removing the engine from the car, and using minimal tools.
Then even the availability of parts. I have a 90's bike now, and the only source of parts is a forum, and thankfully it's a bike that many were made, and it shared parts with a few other bikes.
Bikes aren't cars - parts are more scarce and more specific on a per-bike basis.


