Agile - Isn't It a Good Idea?

i feel like when extreme programming into agile and stuff came out, they were arguing that either our assumptions about where costs happen was wrong. And i can't remember if they were saying it isn't actually that way, or it shouldn't be that way. The more, the worse design your system has, the more expensive it is to make changes. You see it when you have to change things. I mean, thisis what martin's doing with schala three right now. He exclaimed, oh, i have this great idea. And he's not saying, oh, but we're so far down the line, the complexity that's going to cause is is prohibitive, so i