Very pointed article in Wired 14.04: Geekonomics - Why abundance sucks.
Looking at the development of multiplayer games, one can observe the move from utopian worlds where all is free - and therefore everything can be done, but this starts to get boring - to worlds where scarcity plays a role - and where the players again have a goal. Players seem to find that more interesting - but as virtual worlds have no inherent scarcity (as our poor old real world), it has do be designed in ...
So, are players only looking for scarcity because all of us are so used to it and take it for granted?
Or would we also be bored in a real world where everything is free (like in the utopia where machines do all the dirty work for us)?
Anyway - one resource remains scarce for all players currently: time - and that is where the competition between the games lies mainly.