I have a coworker who has the full suite of apple products. He really loved android when I showed him my phone, but he mentioned the same thing… Doesn’t want to have to learn a new system.
Then you have the demographic like my fiance who has an iPhone 4 and is going gaga over the new iPhone 5. Why? I have no idea other than “it looks nice”.
Basically rooting gives you admin priveledges on your phone. You can be rooted still running your stock ROM. A ROM can be thought of as an operating system package. Think of different versions of windows bundled with software and various tweaks to improve speed/battery life etc.
To root and flash ROMs you need to install what’s called a recovery. You can kind of think of that like the installation screens that windows or other OSs load into when starting an installation. Except it’s permanent and lets you install whatever you want. You can get into it by holding a button, usually one of the volume keys, during boot up.
So basically the process is Unlock Bootloader -> Install a custom recovery -> flash Root, or flash rooted ROMs, or flash customizations
There are tools out there that will do all this in one click with the phone connected to your computer. Check the “Android Development” section of your phone’s forum on XDA developers.
Companies like HTC even give you instructions on how to unlock the bootloader straight from their website.
My inner nerd made me root my One X and put Jellybean on it as soon as I got it lol.