http://www.connecticutblaze.com/hockey-goal/can-anyone-tell-me-why-the-goal-crease-in-ice-hockey-is-called-a-creaseIt is called a crease because originally, the lines which demarked the area were physical indentations in the ice (carved into the ice with a stick or skate balde), ie. they were "creases" in the ice. The goalies themselves carved the crease lines so that they could quickly look down (or use their peripheral vision) and know where they were standing relative to the goal – much quicker and better than looking back. It was not always the case that goalies were by rule protected in the crease (though the players themselves, via intimidation, have almost since the beginning of hockey enforced the idea that opponents would not take shots at their goalie).
The area within the physical indentations became known as the "crease area" or "crease." Later, to make it visually clearer to fans, they painted lines on the ice, and the rules evolved to give goalies protection while they stood in their crease.