Humidification can protect your investments
Like many people, the largest investment you most likely made or will make in your lifetime is the purchase of a home. Keeping the relative humidity of the air in your home at an appropriate level will prevent a wide variety of damaging effects. If the humidity in your home is too low, any wood products, such as hardwood floors or furniture, etc. will start to split and crack. This is because as air in your home becomes drier it pulls the moisture out of the wood. As the wood becomes drier, it shrinks, leaving cracks or splitting seams apart.
If you home winds up with too much humidity, it can increase the growth rate and spread of a wide variety of molds. It will also greatly accelerate the rotting process of many woods and other structural materials.
Humidity not only affects your home itself, but also a wide variety of contents. For instance, many musical instruments, when subjected to low humidity will warp, and will no longer be able to be tuned properly. This can get to the extreme of making the instrument no longer functional at all.
Low humidity is the main cause of static electricity in a home. Dry skin and dry carpets are great for creating the friction required to send sparks from your fingertips into anything you touch. With all the highly sensitive electronics equipment (from stereos and tvs to computers) in homes today, static electricity can be a major threat. It doesn't take much of a spark to harm that expensive piece of electronics.