There is a misconception in the media about the importance of a camera system versus an alarm system. The easiest way to understand why an alarm system is more important when protecting your belongings is to compare the two.
Think of an alarm system as a preventative tool. When an intruder breaks in, your alarm system will make a lot of noise. This not only notifies you and your neighbours to the break-in, but is often enough to drive an intruder out.
A camera system is designed to show you what happened after the break-in has occurred. Particularly in a private residence, this is not going to be very helpful to you in an already stressful circumstance. Generally you will want to prevent an intruder stealing anything in the first place, rather then watch them ransack your home.