cogadh: Actually, they are only there as a leftover tool the developers used to test the game during development. They get left behind because it is just easier to leave them there than it is to pull them out. I don't think any developer out there really "wants" you to use them, they simply don't care, nor should anyone else.
Well sometimes they also leave them in there for the fun of it. The Blizzard cheats in their RTS games are often given ironic and funny names or do silly/ridiculous things for instance. I agree that most were originally testing tools, etc ... I just thought I'd add "devs having a sense of humor" to the list of reasons why (some) cheat codes remain in the game or exist at all. :) So most of the time they're only funny once or twice, but I still appreciate the effort.
------------
Using cheats in games are not my style, especially my first time through, but whatever makes ya happy in your single-player experience as the saying (sort-of) goes.