YES!!!
I'm sorry for everyone who may find this offensive, but I agree that Loomis has made enough good points to actually be called the only voice of reason in this thread.
Keeping an opponent from winning an advantageous position is a perfectly viable option in chess. After all, actually winning a good game requires skill and precision, and if you can't provide that, you shouldn't have the full point. It's not the rules' fault if a game is drawn by a perpetual, because if you would abolish the threefold repitition rule, that would just mean one player keeps checking his opponent until one of them gets up and walks away in disgust.
There are much cheaper ways to end a game early on, the most common one being that of two players agreeing on the draw before even 20 moves are played. People have tried to formulate rules against this in tournaments, but so far they have not been overly successful.
I don't understand how one can even begin to think that any act(that is logically within the rules) stopping your opponent winning could be construde as cheap/unfair/unsportsmanlike.
Imagine what the rules of chess would look like if you added in a clause that said "playing for the draw is prohibited" which is pretty much what your asking us to say we agree with.
In my opinion the rule saying these situations result in a draw doesn't even need to exist... if some one has put me into a situation where I am forced to repeat the same two moves then I'm going to figure out pretty fast that the game is a draw. Outside of the perp check if both players are unwilling to move outside of their current positions then the game is a draw. It just makes sense. Anything else is illogical and would take the perfect logical game which is chess and cheapen it.
Apologies for the rant.