Banning land mines is a waste of time and effort and will be ultimately fruitless. Land mines are cheap and easy to make and will be made and used, even if they are not manufactured and sold in mass quantities. War is ugly and nasty and evil and horrible. There is no way to make war nice, nor should it be. Efforts to make war nice should instead be spent trying to end war and suffering directly.
I'm not a soldier, so I'm not going to lecture on the uses of land mines. I do know, however, that there are uses of land mines and as long as soldiers from my country are fighting in wars, I want them to have the tools to fight as effectively as possible so that they can end the conflict as quickly as possible. There's no way to stop someone from rigging up explosives to some kind of tripwire or rigging up any other kind of booby trap. Creating International Laws to ban certain kinds of weapons will do nothing but prolong war.
As I said before, war is ugly and violent and people die. It's a terrible, terrible thing. There is no way to clean it up and make it nice and tolerable. The weapons used in wars are terrible and ugly. Unless you can get soldiers to use whiffle bats and nerf balls as weapons, trying to regulate some weapons is silly. Land mines are horrible and terrible. So are rifles, bombs, grenades, and machine guns. Classifying a weapon of war as being more terrible or less terrible is silly.
As an afterthought, I'll add that weapons of mass destruction are probably qualitatively different from most other kinds of weapons in that they typically kill large numbers of people indiscriminatly. While I still hold that no weapon should be banned, per se, using weapons that might destroy entire cities or kill many civilians at once should certainly be used only as a last resort. If nothing else, they could escalate a war into an orgy of mutual destruction, leaving no winner.