A flexible game = exploitable game?

Yes, we know that exploits are terrible things that will ruin a game totally. What Im getting at here is:

If a game cannot be exploited, it is so balanced that it is unflexible and gives almost no freedom to the players to think creative ways to play it. For example, if movement around the world map can only be gained through missions, there will be no Droknar runs. That will certainly solve alot of complains regarding those runs. But at the same time, GW world is no longer flexible where u do not have the option to skip missions you wish not to do at that moment.

So what I want to know is, if there is such a existence that a game is flexible but not exploitable at the same time? Both's existence seem to depend on one another.

p/s. This is not a complaint or anything. Its more of a thinking topic that comes across my mind.

Where is the suggestion in this? Mod can you please move this topic?