Agonistes, so you're basically saying its so crappy that its just nice to have the AI waste his time on it ?
I'm going beyond that. I'm saying the only rational explanation for its existence in the game is that the dev who created it kept losing on SID, and the other devs were laughing at him, so he (or she) created it for the sole purpose of increasing a player's chances of winning - hence, a cheat. Its cost is nowhere near its value, and the negative margin between its cost and absolute value is greater than for any other wonder by a considerable amount. For such a pile of crap, it comes very early in the game, and most of the AI civs seem to attempt to build it, thereby wasting a heap ton of shields during the most critical age of the game - when the early expansion is still occurring.
Even if its effect was permanent, it would still cost too much.
If you doubt me, play 20 SIDs with it, and 20 without, in that order, just through the first age, and take note of the difference in rate of expansion for the AIs. In the 2nd 20, you will find yourself having opportunities to settle in spots where you did not before, and catch yourself thinking, "I can't believe I beat the AI to that spot with a settler."
Now, its been my experience that the Native American civs are the quickest expansionists. Playing with 31 civs consistently for a number of years, before I tweaked the game to eliminate them, without fail, but with the exception maybe of the Aztecs, the NA civs always had the largest civs following the end of the expansion explosion. So its possible that the ToA was an effort to slow down those particular civs. Which of course didn't work - it slows down every civ. Except the player's. So I guess there are two possible reasons for its existence. Either way, it gives such a boost to the player's chance for success I consider it a cheat.