Dropping your phone can destroy it too, so no one should ever pick theirs up, right?
I think you mean no one should drop their phone lol. Good advice.
With the exception of over clocking, rooting your phone is very very unlikely to damage it. In some cases you could be blacklisted from updates or simply not receive them but android updates are so far and few between you won't miss much.
The biggest risk is you are trusting the people who wrote the software not to seriously rip you off and steal everything. It's very hard to even detect this kind of attack.
That said if you are the least bit curious and follow some simple saftey measures you should root or jail break your phone. It is bs that you own a computer (phone) and the manufacturer tries to say you can't do what you want. Would you put up with a skateboard or snowboard that the manufacturer tried to make changes illegal? Or a car where the manufacturer tried making opening the hood a crime? People should take and interest and learn if that's what they want. It's your phone.