Honda probably does not make a radiator guard standard because people continue to buy the motorcycle without it. Honda likely has no incentive to increase manufacturing cost by adding a radiator guard because it won’t positively impact sales or reduce Honda’s warranty costs.Installed a radiator guard in an attempt to keep the radiator bug free. Kinda wonder why Honda doesn't make that standard? Maybe they don't have insects in Japan like they do here.
However, it would make sense from Honda‘s point of view to offer a radiator guard as a genuine accessory and charge something like $150 for it plus an additional $50 for the necessary installation hardware kit.