The primary difference between that 100 year old house and the new 2012 house is indeed the structural materials. Remember that picture from Katrina with the 100 plus year old house still standing while the development built around it was leveled? That is why there is a ton of steel in these new houses, to reinforce the wood used to build them. The old wood needed no such reinforcement. And yes, I also believe balloon framing and allowing the structure to breath is something lacking in today's construction. At least in places like Florida.
I tend to disagree with your first statement. I would say that the primary difference is craftmanship. I was taught the proper way to build, but when things were booming, it was impossible to adhere to those standards. When I started out as an apprentice, we would be on a slab for about 6-8 days - nothing to dried in & punched out. At the peak of the boom, (I was now a PM with a national builder), my production schedule, set by people sititng in an office, told me I had to have the houses up in 3 days. So how do you make up the time? Instead of crews making 1 trip and doing everything, the framing process was broken up into about 3-4 different trips so that the money would stay flowing.
What we lost was:
1.) Accountibility, the framing sub would send different crews that would always, ALWAYS, bitch about the work that was done.
2.) Dependability - no one wanted to come do punch work - they had already collected their draw and punching out homes costs money and time (read money).
3.) Ability - due to the massive amount of work that was being done, pretty much anyone who could
swing a hammer
carry a nailgun was working. We were lucky if one guy on the job could read prints.