I never used the cheat mode in Civ 2, but I voted Yes. It seems to me that "honesty" has nothing to do with this, and "cheat mode" is a misnomer: its really a powerful tool for testing mods. If you want to play the game without "cheating" (as I do) than simply do so: the presence of this tool would in no way force anyone to use it. If the name "cheat mode" bothers you, maybe they could call it "Modify this game." And as I recall, if you turned on "cheat mode" in Civ 2, you became ineligible for the high score list. Presumably, in Civ 4, you also couldn't use this feature in the middle of multiplayer games.
Besides, even if someone wanted to use this to "cheat" rather than to test a mod, why should I care? Nobody appointed me to be Honesty Police. I say put it in: I'll never use it (unless I somehow get a lot more free time and decide to try to make my own mod) but I think it should be there for the modders' sakes. No offense meant to anyone, but I fail to see how the presence of this tool "ruins" the game for anyone: unless someone cheats at multiplayer, how does what anyone else does with their game affect my game experience at all?