Sure, they look innocent enough, just sitting on your lawn, with their fishing rods, or shovels, etc. But, behind your back, when you are asleep at night, they sit around, preparing for that day when opportunity arrives.
Lawn gnomes are a vital part in securing your home from burglary. Scientific studies have proven that 9/10 times the would be robber will just skip your house, believing you to be a victim of terminal bad taste.
They're also useful for keeping stray animals from taking a dump on your yard.