External ip address?

Totally agreed

Isnt it a bit difficult to do though its not like people dont have router firewalls and windows firewalls?

The External IP address will identify your ISP and general (city) geographic area, and even that is not certain. Your personal information, such as your address, is known only to your ISP and they will only release it with proper legal authorization.To find what information is shown to others for your Ip address use GeoLocations tools or visit site like IP-Details.com .
If a hacker wanted to mess with you, they could take your IP and do a port scan on your system/network looking for things to exploit. If you have a good(updated) anti virus program and a good firewall installed you won't have to worry much about that though. If your Ip is dynamic you don't need to worry,the Ip will change if you restart your modem/router (mostly) or over a certain period of time.

Most people are behind a router anyways, and don't forward their ports unless they're running a server (and most people aren't running a server.)

If you aren't running a server don't worry about it. If you are, make sure all your shit is updated and the server isn't reported as vulnerable.

I am running a small server for minecraft. My isp says i dont have a static ip but i tried unplugging my router for about an hour and plugging it back in and i still had the same ip and i did the ipconfig release and renew and still have the same ip but i dont really care.