There are 2 types of users of technology, those who take and use the technology as it was delivered to them (the average user), and those who look at the tech, and see the vast potential waiting to be unlocked (geeks, nerds, Superusers). This holds true for Smartphones, even more so.
Even back in the old Windows Mobile days, smartphone Superusers have been cooking up custom ROMs, and finding workarounds to unleash the full potential of their devices. When the iPhone launched, hackers saw the true potential past the very limited and locked down software that the iPhone shipped with, and thus "jailbreaking" was born. When Android was born, developers saw the same thing, and went to work creating custom ROMs, and workarounds to exploit the powerful hardware that was being presented.
Even though Android is "open source" software, it is still hamstrung by many factors, including the OEM's custom UI, like HTC Sense, Motorola Blur, and Samsung TouchWiz, which, while providing some innovative functionalities, also tend to be very obtrusive, and resource hogs. So, the developer, and hacker comunity began creating new versions of the Android software that optimizes the hardware, while retaining the useful tweaks of the OEMs.
Before installing any of these awesome tweaks, you must obtain "root" access, which basically gives you control of the system files of your Android device. Obtaining that access can be very easy, or very difficult, depending on your device, and whether or not the manufacturer of your device leaves the bootloaders unlocked. The number of ways to gain root access is as numerous as the number of available Android handsets. Since this is a WHY, and not a HOW TO, article, I am not going to post them all here. If you really want to root your phone, the best place to find the method for your particular device, is the
XDA Developers forums. Just search for your device, and go to the section labeled Development, The walkthroughs are very thorough, just be sure to read EVERYTHING completely, and follow the instructions exactly.
Ok, now to the reasons to root your phone.
Performance Update
There are just too many flavors of Android on the market, with every OEM or carrier adding their own personalization and customization to devices. While these may appeal to some, they do not let the device take full advantage of what the hardware is capable of. With root access, you can actually tweak the OS to behave entirely differently, and with developers like Cyanogen working on custom ROMs and mods, people have actually reported significant performance boosts. Take the Samsung Galaxy S, first generation. Samsung has officially stated that it will not get the Android 4.0 (Ice Cream Sandwich) updat, but thanks to Cyanogenmod, the Galaxy S is getting an unofficial update thanks to the CM9 custom ROM.
Hardware/Software Interaction
Most Android devices come with hardware that is very powerful (many of the high end devices are more powerful than our PCs of just a couple of years ago), yet the OS limits them and becomes the bottleneck. By rooting, you actually remove the bottleneck and hence can take full advantage of your Android. For example, overclocking a device’s CPU is fairly simple and rather safe thanks to many third-party apps, yet the OS does not allow it natively. Overclocking can only be done with a rooted phone. Or suppose you want to use your mobile’s LED as flashlight but cannot because the manufacturer
won’t allow it? Rooting allows you to bypass these limitations!
WIFI Tethering
After having rooted your device, you can also use WiFi tether to share your cellular data connection with your laptop or PC. The application works with ad hoc connections and will get you up and running online on your laptop in no time. There are numerous apps for this, but it is also included in the builds of several custom ROMs.
Enable NFC Capabilitie
NFC, or Near Field Communications, is a technology that is being built in to a lot of devices, but is software disabled by the carriers here in the US. Root access allows you to bypass this setting, and turn on the NFC capabilities of your phone, and use it for many things, such as making payments by tapping your phone on a NFC enabled payment station, or using NFC tags to make certain things happen on your device. Again, generally only available, if you root your device.
Root only Apps
There are tons of very useful apps in the Google Play store, that can only be used on a rooted phone. Titanium Backup, setCPU, cacheMate, and many more. These apps add functionality and control over your system that just isn't available without root.
and finally......
Because You Can!
I am serious, this is actually the best reason, IMHO. You have an awesomely powerful device that you have paid for. You have the right to modify or change it in any way you like. The device is your property, and you would naturally want to see it working at its maximum potential. Hence the point of rooting.
With the each new version of the OS, some of these reasons will become obsolete. But the newest version will not be pushed to all devices. While the OEMs, Carriers, and Google continue to talk about reducing the fragmentation in Android, until it happens, a rooted device is the best option you have to keep your device running up to it's optimum potential.
Last, please do remember that rooting voids your warranty. Although you can always go back to a stock version of the OS, it is risky business, hence proceed with caution.