Well, you know, the Gremlins being effective for the first three weeks of the game is a pretty strong argument, and about the first-level units at the end of the game... well, I use them. Because there are so many of them, and after someone launches a counterattack, you can finish off someone very effectively... and you can only look for someone else to add to your army if you have another castle with a good growth rate, and if it's worth it to lower your morale.