I've been in the hobby for 26 years. Apart from the things mentioned above, I would also add that one of the biggest advances in that time has been 2.2 inch wheels & tyres for off road cars. Pick up a rear wheel and tyre from today and compare it to a 1.9 " rim and Yokomo or Tamiya tyre that we used in the past - massive difference.
(Yes, I know this is the on road forum. Just adding to the list).