RE: Excuse me, but this is a little funny...
not wrong, but only partially right, the OS sometimes does take a lot of RAM but its not hidden. Majority of the stuff that gets placed in RAM are things that need to run for the OS and also programs you are using. The advantage of this? RAM is significantly fast compared to hard disk space, So the more RAM you have the more things that can get stored into the RAM so that it can be accessed blindingly fast. This translates to fast performance. Increasing your RAM usage has such a big advantage (provided you don't reach the upper limit of what you have available of course)
And it is true that for an average user (lets say primarily for internet browsing), one might not end up using lots of RAM. Jhampa did mention about film editing, more Ram might come in handy here. It will of course depend on the OS being used, the software, and so on.
I wouldn't go as far to say that 3GB and 4GB just future proofs you, however, aaasolanki you do make a pretty fair point.