paladin181: Why stupid? Because they don't want people putting out products of dubious quality bearing Nintendo's trademarked intellectual property? The monsters. They're protecting their property. Nothing wrong with that.
Not only is there nothing wrong with it though, but trademark law requires it. If someone utilizes one's trademarks in a manner that is not considered fair use by the law, and also does not have a written licensing agreement that is legally binding to permit the usage, then a trademark owner is required by law to contact the infringing party and require them to either cease and desist using their trademark, or if they wish they can also offer the option to allow the third party to license their trademark. The latter is not required, and companies may not wish to allow third parties to use their trademark or branding at all however.
This only affects trademarks, not copyrights or patents however. The general motto with trademark law is "defend it strong, or lose it" and there are cases of both out there. The down side of it is that when a trademark owner defends their trademark as they are required by law to do in order to keep it, they will almost always be seen as a big evil company in the eyes of the public, and possibly in the eyes of the person violating the mark - both of whom generally know absolutely nothing about how trademark law works and the requirement to defend it strictly against infringement and dilution, no matter how well meaning the infringers are.
Copyrights and patents work differently. The owner is not required to contact the infringing party to stop them from infringing in order to protect their property. They can either silently allow it, or they can pursue it legally if they wish to put an end to the infringement, and they can wait years to do so possibly giving people the impression that they were ok with it, then suddenly slamming a huge lawsuit down when it is economically beneficial to them to do so.
Most companies with experience in these things take it very seriously and send out legal notices promptly for known trademark violations. They may not do so with copyright or patent violations however, instead waiting for the infringer to become profitable with whatever they're doing so that there is money to be made by suing them.
Intellectual property law is a big ugly mess, but it is what it is.