Well, I mean who dictates your designs? S. John Ross once told me that if you design to limit abuse of your system, you are designing to limit use of your system. It's something which is not as intuitive as it seems. Putting in a rule which could be abused requires trust in your players. If you know your players, this works uniformly well. A GM knows her players. It is another thing entirely to publish a ruleset with rules which could be abused. A published game designer does not know who will be playing games with his rules. The trust must be blind.
Do game groups merit blind trust? I don't know. I don't know if I merit blind trust. Thing is, I want folks to have the best possible experience they can, and when a good GM and good players get together with trust, it's a beautiful thing to see. I decided some time ago to design for the good players - the ones who see how a rule could be exploited and decide not to. I expect them to use the rule to do cool stuff, not screw with it.
Jesus said "The poor will always be with us." I feel the same way about bad players. If I design for bad players, I limit the enjoyment good players get from my games, and I would rather allow the bad players the ability to push things too far. I put my trust in the groups, and hope they don't disappoint me.