Its a bit crazy this has not happened sooner, since my 486 ram has dropped in price fast and capacity has gone up, but since I remember putting 4gb in my machine about 3 to 4 years ago it seemed to have stagnated, the price going slowly down but capacity staying the same, we should all be on 32gb of ram now.
I am sure if that were the norm the 64bit OS standard would have a much tighter hold and we all would be enjoying the benefits.