Advances in metallurgy and the ability to produce lighter,stronger and more complex pieces has had a lot to do with what we have now.The modern crankcase is far superior to the old stuff as are the alloy materials used in our modern bikes.Aluminum fork stanchions,nikasil lined cylinders,alloy bash plates etc etc.And without modern computers,none of this would be possible.
Love my Ossa tr280i,but i really like tinkering with my ty175 in all it's simplicity.