I feel compelled to say something as I do try and stay away from the weight weenie argument most times.
I just don't get it, for me I cannot ride a bike that light as it doesn't meet current UCI requirements but more importantly I am not sure why, as an amateur cyclist, you would. I understand the argument that some people make to get justify it but too often I have seen people crash and wreck a frame on a group ride etc. How would you explain replacing that to someone. Perhaps I just look at the utility of riding and the dangers that come with it. If you can afford to throw out and replace a damaged frameset worth that much all the power to you (I have a friend that went through 3 S-Works frames last year) but I just don't get it.
Secondly and more importantly too often I have stopped at the store to see guys discussing their sub 15 pound bikes and all their weight weenie type stuff only to ride by them on the first climb on my 15+ pound bike with my 32h training wheels and other mandatory training gear. I can just imagine the thoughts - damn I just paid $12,000 bucks for fata$$ to drop me on his fata$$ setup bike.
If you are a pro and don't pay for it that is a different story.
Just confused, that is it.