There are a lot of other species of fish that are better eating than striper. Also, cutting and packaging a striper is a ton of work when compared to buying a cod or haddock filet at the market. Its easier to buy a fish than cut a fish.
A slight digression, but related, it takes a couple of hours to pluck, cut and package a turkey. You can buy a nice, clean turkey in the market with no pin feathers that is ready to pop into the oven for under five bucks. To further digress on this digression, the special cartridge that you should use to kill this bird costs $8 for ONE! Lordy, don't miss.