Antipersonell mines currently have such a high TK rate that making them less visible is out of the question (yes, I dare say that with a very high degree of certainty even though I'm not a dev). 7 out of 10 times I lay an AP mine it kills one or more teammates. Those things are deadly. There's also the fact that antitank mines are used far more often, and as such, I think people assume mines they see are antitank, for then to step on them. Just a theory.
Is it possible to have them appear on the minimap of friendly forces? I think that could reduce the TK rate significantly. That, and calling out a warning when you're laying them and telling people not to step on them, of course.
Oh, and if anyone wondered:
Antitank mines are crescent-shaped. They are carried by the HWS class.
Antipesonell mines are triangular, with flashing lights, and can stick to building walls. They are carried by the Support class.
"One of the bitches actually gave birth while she was attacking, and her puppies joined in on the carnage."
--the awesomeness that is Boatmurdered.