The protocols for space walks are also very similar to deep sea divers. The suits have an internal air pressure lower than the space station (for many good reasons). In order to avoid getting symptoms similar to the bends, they have to spend several hours pre-breathing pure oxygen etc. This means they can't just put on a suit and go outside in an emergency - it takes planning and time.

Could you explain why this is the case?

This section explains pressures: http://en.wikipedia.org/wiki/Space_suit#Operating_pressure

This 4 minute 1987 NASA video explains suit history: https://www.youtube.com/watch?v=X4WK6IUQ7QU

This page explains the protocol and over two hours of pre-breathe: http://spaceflight.nasa.gov/station/eva/outside.html

This section (4th paragraph) explains what happens when a space suit is pressurized: http://en.wikipedia.org/wiki/Gemini_9A#Objectives

Quote: After pumping up his pressure suit to three and one half pounds of pressure per square inch, "the suit took on a life of its own and became so stiff that it didn't want to bend at all." He struggled to move inside his stiff suit.

Very informative, thanks!

The ISS is pressurized to match Earth at sea level (it's designed for long-term habitation), and the pressurized modules are built to withstand that pressure.

Making a spacesuit that could handle the same pressure would require it to be much heavier and more rigid. Cutting the pressure makes it much easier to work in.

My guess would be that full pressurization makes the suit too rigid.

Probably too dangerous to bring back inside with several pounds of ammonia in it. Might as well just let it RIP outside.

Since it's not so easy to take it down to the shop to check it out, that's probably the only way they can find out what went wrong with it.