Common practice is not always the best practice

One of the things I ponder frequently, particularly when I am doing demolition work, is, "what were they thinking when they built this?!?"  My pondering does not stop their, however.  It is followed by the thought that someday, decades from now, someone may be demolishing some of my work and think, "what was that guy thinking when he built this?"
It is easy to question the common practices of the building profession of yester-year.  Why would you ever paint with lead-based paint?  Why would you use asbestos?  Etc.  Yet, I have to give my predecessors in the building trades the benefit of the doubt that they were using the best, safest products that were available to them at the time.  After all, lead-based paint is an extremely durable and quality product-still used in many industries.  Asbestos is a great fire-blocking, insulating material - it will function well for years to come if left undisturbed.
We do the same today.  We use the best products and practices that are available to us.  Screws have replaced nails, acrylics have replaced alkyds, we use lumber that is sustainable, energy that is renewable, and run job sites that are safer.
One obvious advantage that we have for us today is the advances in science.  We know much more about products now than we did before, and we can engineer stronger, safer, lighter products than people ever imagined possible.  Yet, what we do lack is long-term studies of these materials.  After all, it wasn't until people started getting mesothielioma and lead poising, decades after working with those products, that their use was questioned.  Lead paint was banned for use in homes in 1979, but look at all the recent attention it has been getting.  Think of all the homes that were built during the most recent housing boom (before the 2008 down turn), that were built with relatively new products and techniques.  Will all those homes someday be considered terribly unsafe?  Will latex paints be the new lead?  Fiberglass the new asbestos?  I guess only time will tell.  In the mean time, we as builders will remain committed to using the safest, strongest, and best practices that we can.