Whenever your bolting Steel into Aluminum, those Torque values are stated to keep the uninformed and unexperienced from having to learn about Heli-Coils and the application there of. An even amount of engineered force by the fasteners on even an engine case, helps to keep from imparting a misalignment (tweaking) in the bottom casting for the bearing journals. Even the floor mounting bolts for a 6 Ton milling machine are thoroughly checked for a soft foot and a specified Torque application, at least in the Aero-Space machine shops around me. Water pumps, installed correctly, deal with "pipe strain", if the plumbing attached to the pump is not relaxed, the pump usually will experience premature failure. Ultimately, torque values should be followed by all, because a failure of a component on a motorcycle can be catastrophic, as we all should know..
