Jon Shafer, currently at Stardock and formerly of Firaxis, has a great article on his blog about why limits are good things. It also explains briefly why boats (pictured) are awesome.
Game design is the art of providing enjoyable frustration (credit to Andrew Meyer for that phrase) and the frustration part is something that often has to be tiptoed around or hidden from players. Most players think they’re just in this for the power fantasy of it all. Shafer gives a few examples of how limitations and scarcity create value. Read the article here.