Motorcycle parts aren't very standardized across manufacturers
I think going so far as to make crankshafts interchangeable isn't a sign that a manufacturer cares about standardization though. A crankshaft is a central component of an engine and can drive rider feel, power delivery and performance of the vehicle.
There are some manufacturers that are very good about standardizing internally though. Suzuki has been a great example. Rectifiers, various switches, front ends, controls and even some engine components can be very interchangeable across models.
Most manufacturers and are not as thoughtful though.
Cross Brand Standardization
The simple answer, it doesn't exist. Other than brake mounts, calipers, sprockets, chains and headlights there really isn't much of this. I don't see this as an indictment though. From my perspective the car industry is about the same.