There are many reasons. First, you can use third party applications to enhance the functionality of our iphone. Again, you can switch to any service provider in any country.

iPhone app store has several apps for my use. Why should I still to jailbreak my iPhone?

Good question. The apps at the Apple store are the official and restricted software only. There are many other programs that you will want to use and are available at other places like Netshare. You can only use apps from elsewhere only if you have a jail broken iphone. For example, MXTUBE allows you to download YOUTUBE onto your phone but it is not available at the app store by Apple. So you see why jailbreak an iphone.

Again, jail breaking the phone allows you to customize your phone in many ways. If You dont like the firmware wallpaper for example, you can install a customized one. With a jailbreak, you can also turn your iPhone camera into a camcorder for recoding of videos. If one would ask the need to jailbreak my iPhone, the best response will be – you have unrestricted use of your iphone.