If I had 100 bitcoins in my wallet and my hard drive was irreversibly destroyed (eg. in a fire), but I managed to write the private key on a piece of paper elsewhere, would I be able to gain access to my 100 bitcoins?

An example private key I found on the bitcoin wiki is something like this:

5Kb8kLf9zgWQnogidDA76MzPL6TsZZY36hWXMssSzNydYXYB9KF

And if so, then why is the process of creating a paper wallet much more complex than just writing down the private key? The bitcoin wiki suggests downloading and booting from a live CD for example and all of the paper wallets that I've seen have additional information on them like QR codes and the wallet address even though the bitcoin wiki says that a wallet address can be generated from a private key anyway (but importantly, not the other way round).

Also, if someone is using something like the Electrum wallet then are there any differences?