Tropical Beach was designed and released over two years ago. What do you mean by the above?
They still knew that they were creating a "unique" exclusive (as opposed to a card that had been or would be released elsewhere with different art) - this is the risk
always taken when releasing such a card. Even when releasing an intentionally bad card, the game's designers know that the card pool is not static and they have to consider it for all future card interaction as well as rule changes.
Because it can be difficult to keep track of so many different cards, and it is likely that the game's designers never really "expect" to change the rules (I assume that they want to find something that works and stop fiddling with it), it just makes sense to not create a unique exclusive. Creating a non-unique card like an alternate art or treatment (like a specific holofoil pattern) promo of an existing or soon to exist card is perfectly fine for an exclusive.
This problem has always been a problem for as long as such promos have existed, but like so many things it wasn't as big of a problem.
Oh, and FunnyBear, thanks for proving my point:
A TCG isn't a game of chess; I question messing with the tournament rules to so heavily favor a champion, but that still doesn't compare with altering what one uses to play the game. As we all know, you don't get special chess pieces that alters how the game is played for being the World Chess Champion, a special board, etc. Now, if you really do want TCGs to give such an advantage to players... you're allowed to want that. You don't get to dismiss people rejecting that just because "life isn't fair" or because you believe some players have "earned" that. At best you can claim the current success of the game indicates that there is sufficient demand for your preferences...
...but then we have the issue of "How long does it take for the customer base to react to a bad decision?"