In some cases, landmines are justified. There are thousands of landmines in the demilitarized zone separating North and South Korea. These mines are protecting the South from a Northern invasion. Although landmines can be used against civilians, all weapons can be used in this way. We should no more ban landmines than any other weapon of war.
There is no doubt the landmines left from long forgotten wars are a major problem for ordinary people long after a conflict has ended. Land mines are no different from a nuclear device or AK-47. They are a deadly tool of war. In terrain denial you really only have 2 options, walls and mines. They provide an invaluable tool to militaries around the world. However, if a mine is not properly removed/detonated after the conflict is over, whoever laid it should be held responsible for any future fatalities. With GPS location, mine can be made as safe as any weapon of war can be.