Yes, emergency generators that are permanently wired into your home or structure pose safety hazards that you may not be aware of. Transfer switches are required because electricity from the generator can be sent through the meter base and into the distribution lines. This could be life-threatening to workers, neighbors, children, or animals in the vicinity of a downed power line. In addition, when power is restored it will flow back to your home, and can seriously damage or destroy a generator that does not have approved safety switching.
Portable generators can also be dangerous if operated improperly so please consult the owners manual for proper operation.