In this day and age it seems you can’t find a new phone without an eager group of developers ready to support it. Some people come to Android and may not have the slightest clue of what rooting and flashing custom ROMs/mods/kernels is. (I have two of them in my very own household.)
If you were ever curious as to why you should root your phone and what benefits you’d get from it. It isn’t without its cons, though. AndroidForums.com user cammykool reposted an article of Locker Gnome’s, a very good breakdown of the pros and cons of installing custom ROMs. Many people have many different reasons.
For me, it used to be about making the most out of whatever custom skin came on top of any phone I owned that was not supported by Cyanogen. Now that I have a Galaxy Nexus, I find that I don’t even have a desire to flash any ROM, though I do keep root handy in case the urge pops up (and I do rely on root-specific apps, ROM flashing aside).
What about you? Take a look at the article over at AndroidForums.com and see if some of the pros will apply to you and to see if some of the cons will deter you. After that, be sure to navigate to the All Things Root sub-section of your device’s section on AndroidForums.com to get started on rooting and installing some ROMs that may be of use to you.