Mines are alright in PVE by virtue of anything being alright in PVE.
PVP is a different story; they are really only there to annoy the enemy. Tricobalt Mine will stun them so that is useful, and Chroniton mines have a chance to slow anyone hit by them. Cloaked Tractor Beam Mines can also slow. With the exception of the Tricobalt Mine, no mine does any sort of appreciable damage even to bare hull. Thus the Dispersal Pattern tactical powers are largely useless.