I would think that one of the primary reasons for cheats would be to satisify the "what if" curiousity in people.

"What if I had $999,999,999?"
"What if I didn''t have to worry about ammo?"
"What if I could walk through this wall?"

I agree with the notion posted before that it is usually a sign of poor design and balance if people often get to the point where they are wanting to cheat. However, it doesn''t hurt to ALLOW them to do so for whatever reason. In a well designed game, it shouldn''t cross their mind until they get to the point (perhaps after "winning") where they start exploring the "what ifs".

One of the gripes about Roller Coaster Tycoon at first was that there was no "sandbox" where you could just build a park from scratch. You HAD to start with one of the scenarios and achieve the victory conditions (or at least work towards them). They added this later with Loopy Landscapes... but even then, they weren''t true "blank slates" until a patch came out that bypassed some of the checking that took place. I know that, for me, I got to a point where I wanted to just "play" rather than "play". (Nah... that''s not vague, is it?) The point being, while I liked the scenarios and finished most of them, I wanted to be able to play "what if".

Dave Mark
Intrinsic Algorithm Development
"Reducing the world to mathematical equations!"