One of the worse things you can do to a refrigerator is to unplug it for more than a week or two. This could cause your compressor to lock up.
Some refrigerant lines are and have always been very thin, they need to be. Copper tubing erodes when it is in contact with water for a long period of time.
The most common cause for the refrigerant lines to leak, is dirty condenser coils. The coils should be cleaned at least once a year to prevent the air flow from becoming restricted. This causes the compressor to run hot, the refrigerant will also be hot, causeing improper flow. The copper lines will freeze and the ice around them and in them will cause expansion and leaks.