I beg to differ there, pal. In this fast paced world, few people have the time and patience to crawl through games. I mean it's fine for some time, but it gets irritating after a while.
Believe me pal, most of the ppl i know don't "like" a particular game usually because the game isn't fast enough. Same environments and enemies over and over again and by the time the good levels come, the player is already bored.
That's where cheat codes come in. If I happen to buy a game and after playing a few levels, I find it boring, then I just switch to God mode and complete the whole game in a fraction of the time it normally takes.
Do note that I'm talking about not-so-good games here. When playing good games like GTA, using cheat-codes would be a crime. It just ruins the fun.