Hi Ian, you're right about manufacturers not stitching their customers up with bad advice, they'd see a lot of warranty returns if that was the case. However, having done extensive testing they will be confident that under normal working conditions your engine will happily run to 10,000 kilometers (if the user manual says that) before needing an oil change.
Will your motorcycle benefit from more regular maintenance? The answer is, of course, 'YES'.
Ideally we'd change oil and filters every 4,000 to 5,000 kilometers as you said. If you grab yourself a re-usable K&N air-filter you can every year. It's Hygroscopic and attracts moisture, which will turn to acid and eat away at the master cylinder and caliper bores. You shouldn't need to change spark plugs very often, unless you own a carburetted engine and are partial to flooding it. Obviously thinks like tires, brake pads, and the chain need to have a constant eye kept on them.