Why choose the word landmine? What's wrong with, say, a hammer?

Hammers aren't used to exclude people from a path they might otherwise blissfully follow.

You simply aren't using enough hammers!

Though seriously, I think the term landmine is loaded toward using patents exclusively as a troll. A wider analogy could be like a toll bridge, where the builder should be compensated by travelers. Some tolls could be usurious, but that wouldn't invalidate the whole principle.

I guess I disagree with the idea that patents are inherently bad. Like hammers they can be used to build or to destroy.