You are over thinking it. Sure, plastics are on average more expensive to fish than hard baits or wire baits, but neither will last forever. Things like poppers, spooks and other things not usually fished in cover can certainly last years, but jigs, spinnerbaits, and cranks will certainly succumb to wear and tear and other forms of early demise. Senkos bounce off boat hulls or pier pilings much better than hard baits. Not to mention that for those of us who fish around pike, pickerel and snakeheads, they help to close the price difference gap, a hook and a piece of plastic is what, maybe $2, vs $8-20 lure.