Not a bad idea at all, if you have the skills and knowledge. Remember in spec is in spec, doesnt have to be at the high end of spec or even the middle. Sometimes more harm can be done by the unskilled than if things are just left alone.
Honda also recommends you pull and inspect the plugs at 4000 and replace them at 8000 miles
Air cleaner is supposed to be inspected at 12,000 miles.
However I replace my air cleaner and spark plugs every 25,000 with no in between inspections, and they could probably go twice that.