The main objective of the game is to survive and be creative if you want.
In Creative mode, you can't die unless you fall into the void, you can fly, instant-break blocks, and have infinite blocks.
In Survival mode, you have to look for resources and build while fighting off monsters at night. But with an inventory editior such as TMI or NEI, you already have all the blocks at your disposal + more that you can't even get in creative mode, you can mine and build normally and still have the risk of dying.
Before Beta 1.8 came out, there was no creative mode, and when 1.3 came out worlds were not locked to either Survival or Creative and could be easily changed through commands if cheats are enabled.
Now to my point. If any of you have played minecraft before Creative mode came out, did you use an inventory editor and have more fun than in creative mode?
Creative didn't ruin the game. Why? Because it didn't change anything to do with Survival. Survival and Creative are separate things for a reason.
Did we use INV editors before there was Creative? Well I've been playing since early Alpha, and I did in fact use the original INVEdit to test things. But I never cheated if that's what you're asking. This is a dead-end topic.