I don't get all this "wonder addiction" talk, yes, it's not very practical when playing the more difficult levels, but surely there's a lot of people that think the most rewarding part to the game is actually beating the AI in building these wonders. You don't really get the same sense of achievement gaining these wonders through conquest, as you do when you manage to build them yourself. I'm not saying it's a necessity to have these wonders, it's more to do with the fact each person has a differing perspective on what's important and what's not
Lets be honest, most early wonders are obsolete once you have the necessary force to remove them from the AI's control. I very rarely, if at all, have the necessary troops available (other than defensive garrisons) until Knights come into play, why? Because I find it a pain in the ass moving swordsman, archers and spears one tile at a time. I don't bother with Horsemen either as I tend to lose them more often than not.